I've had my Bobcat E50 to the dealer twice trying to get the air conditioner to work properly. So far there's been very little change. The machine has a little over 100 hours on it. I don't know a whole lot about ac's. The low side is at about 20 psi and the high side at best is 170 psi. Before it was brought in the first time, I added about 8oz. of refrigerant. It made no difference to the pressure readings or the temperature at the vents. According to the service manual the temperature at the vents should be between 36 and 53 degrees, depending on humidity. And the pressure readings at ambient air temperature of 86 to 101 degrees should be: Low side 15-33 psi and High side 210-265 psi. When it was being serviced the first time they said that everything was fine and it was blowing 60 degrees out the vents which it was but that's not cold enough to keep the machine comfortable. I then checked the pressure readings and they were off so I had it serviced again. I also told them what the service manual says regarding vent temperature. Before it was brought in the second time I told the service guy that the High side pressure was too low. I also told them what the service manual says regarding vent temperature. When I got it back yesterday he said they put it on the ac machine and pressure was where it's supposed to be and they checked everything out. Put a dye in and no leaks. They said a water drain line was clogged and now it works better. It doesn't. High side pressure is still low and it's maybe a couple degrees colder at the vents. Any ideas what's wrong? I've tried searching the web and can't seem to come up with a low pressure side low or normal and high pressure side low scenario other than low refrigerant which they claim they removed it, vacuumed the system and put the proper amount in, twice now. Thanks, Doug
I would be checking air flow through the evap core . Going strictly by pressures is also not very accurate. Too many variables. I don’t know how that machine is set up but if it has blend doors in the ac heater unit that could be an issue. Low evaporator core air flow will cause the high side to be lower.
You can Google a 134a pressure/temperature chart to know for sure that your system is working correctly. As the ambient temperature changes so will the pressure. The readings you gave seem on the low side. Most a/c systems when working right will be blowing 30 degrees lower than the ambient temperature. Some are better and some are worse. If it has a red dot type a/c system in it. It will never cool enough. Those have to small of a condenser and evaporator cores to be efficient. Also if the heater bypass valve isn't closing then that will negate any cooling. Most a/c systems blow through the heater core first.
I'm not exactly sure how to check the evaporator core air flow. I'm including a picture of the evaporator area with the front cover off. I think it draws air from the cab and from under the hood by the hydraulics.
Oops, forgot the picture.
I checked out a chart and the service manual. The high pressure side didn't seem to change much between 85 and 90+ degrees. At 85 degrees out the high pressure was about 165-170 psi and at 90+ it was about the same. It should be well over 200 psi. There isn't any scenario in the troubleshooting section of the repair manual for the High pressure side being low except for low refrigerant which I'm pretty sure is right where it should be. I do think that it's strange that when I added about 8oz. of refrigerant it did not affect the high pressure readings. My understand is that if there was excess refrigerant the high side pressure should be too high rather than too low.
Good functioning ac system is about flow and conversion. Close off the heater core lines if possible so you are not blending evaporator cool air with the heater core hot air. When the condenser is cooling sufficiently the high side will drop. On average, your high side pressure will be around 7 times the low side pressure.
If you are getting a reading of 20psi on the low side and 170psi on the high side @ 90*F. Then you probably don't have enough freon in the system or the compressor is weak. Make sure that the belt is tight as well.
Are you checking pressures at 1500 rpms? Rarely are a/c systems on compact equipment much to brag about. It is functional, but not optimal.
I'll see if I can figure out how to close off the line tomorrow.
The machine has been to the dealer twice in the last week and a half. Both times they said they drained, vacuumed and refilled the system so hopefully the right amount of refrigerant is in it. Don't know what I can do about the belt. It's tucked away pretty good. I poked it with a screwdriver to see how tight it is, didn't seem loose. The counterweight has to be removed in order to get to it if it needs to be tightened.
Yup, checked at full throttle.
I have never in 25 years of working on ac systems almost daily had a properly working system at 20 psi on the low side charge it until the low side is around 30-35 if it doesn't go up to that near the recommended amount of Freon you have a restriction in the suction side Hooking to an ac machine means nothing only that they dont know how to read guages and bought some time by pushing buttons and walking away for 1/2 hour vacuuming boils out water thats it there is no water in a sealed system when no parts have been replaced Ask them the exact amount of refrigerant removed and how much put back in and compare to the specs maybe the same guy read it wrong twice... Also find another dealer its not going to cool with 20 psi on the suction side
I thought restriction also, but with the high side being low too. I think it's low on freon or failing compressor or belt slipping.
Txv system in TB180FR, 48°f vent temp, engine at operating temp, 90°f outdoor temp. At idle.
That and the internal cab air filter- I see that the machine has low hours, but if a squirrel built his nest in your ductwork, you aint getting the flow the engineers designed. That on its own will lower pressures.
According to the service manual, the system holds 23 oz. of refrigerant. Before I had it brought in the first time I added around 8 oz. of refrigerant. The gauges readings did not change. Doesn't that mean something? I expected the pressure to go higher, but nothing. They claimed that the machine had the right amount of refrigerant when it was brought in. So either they didn't check it or it was low before I added to it. They pretty much said that everything was fine as it was. They sent the machine back without contacting me. I called them and told them that the service manual says it should be blowing between 36 and 53 degrees at the vents and that the pressure readings were low. He admitted they never checked the pressure readings so I sent the machine back. This time they said there was a clogged drain line causing the issues and it was fine now. I asked about the pressures and he said they were fine now too. Nothing has changed. He also said that they put dye in to check for leaks since I told him about adding refrigerant to it. I don't have much choice as far as dealers, it's warranty work and the next closest dealer is almost 3 hours away and part of the same dealership group.
So have you had the machine in the summer before Had it worked well and then not as well ?
The only official way to check charge is to recover and weigh back in charge. If you have a thermocouple you can insulate and attach to the liquid leaving the condenser, you can check subcooling and that is also a valid way to do it but more art and judgement required than the weight method. Otherwise you are somewhat shooting in the dark but it can be done that way too.
I checked both filters, they are clean and no obstructions.
I got the machine this spring. From the beginning I thought that the AC seemed kind of weak. But it became obvious now that it's hot out. It's been in the 90's and humid lately and when I use the machine I try to use it early in the morning because it starts getting pretty uncomfortable as the day goes on. Then I jump into the 25 years old beat up backhoe and use that for the rest of the day, lol.
Sounds beyond my limited capabilities. I do have a vacuum, a tank of 134a and a scale but according to the dealer it has the right amount of freon in it. And when I did add more refrigerant to it, it didn't seem to change the pressure readings.
You are handicapped with this being under warranty.
I didn't notice it was under warranty. Maybe a call to corporate that you have taken it to the dealer and they don't know how to fix it.
Maybe you can sit in another one with your temp gauge or even someone on here can take a reading then go hard up the ladder at the dealer get your salesman involved too
A/C can be more art than science at times and it can be extremely frustrating to troubleshoot. Oftentimes manufacturer service info can be crappy as well. it takes time and experience and a lot of times it can be hard to get that experience. The dealer probably doesn’t have someone with that experience. if this is an orfice tube system make sure the tube is installed and properly oriented. I’ve had one machine brought to me that stumped me for a while until I checked for the orifice tube in place and it was missing, installed one and she worked perfect. It would be extremely conceivable to be missing one from the factory
I haven’t used an ac scale for years. I have better luck going by pressure readings it seems. After a 30 min or so vacuum I add Freon to the high side until my gauges read around 60 or so psi and at the point I fire the system up. If it’s 90 or above I will add Freon until the high side hits around 250. You want your working pressure around there. Once you get to about 220 let it run for a while and see where the system levels out at. Your low side should be around 30 or so psi if if the system is working properly. The key is to add Freon slowly. You can dump to much in and overload the condenser which will cause your pressure to spike way to high. if you hit 150 to 200 on the high side and your low side just keeps climbing while not getting cold air you have a weak compressor most times. On some machines the condenser and condenser fans are strong enough to keep the high side low but you’ll have frigid air at that point. I know the scale is the proper way but as stated I’ve found it’s way more of an art then a science. 170 seems way low on the high side. If you don’t want to vacuum the system and start over I would add Freon until the pressures start to come up. Bring your high side up to about 200-250 and see how it does. If it doesn’t change anything evacuate the system, add the recommended amount back in and keep fighting the dealer.
That's a good idea. I think I'll post in the compact excavators forum and see if someone will check their machine. The dealer told me that he checked another new one they have in their yard and it was blowing at about 54 degrees in 90+ degree temperature. But he also said at the same time mine was at 56. It might do that after running a few minutes but after the machine is warmed up it's around 60.
Before I had the machine worked on the first time, I added about 8 oz. of freon and it did not change the temperature or any of the pressures on the high or low side.
I don't see an orifice tube being shown in the service manual. It does have an expansion valve, could that be causing the problem?
your expansion valve is your metering device (the same function an orifice tube provides) Of course If it has failed it could very well not cool correctly.
I was always taught to add refrigerant to the low side and let the compressor pull it in from the suction side. My personal thoughts would be to get the heater hoses shut off as that will add a few degrees to the vent temp. Next if you can’t get pressures up by adding in refrigerant you’ve either got a failing compressor or a stuck expansion valve. I usually test the expansion valve by pulling a vacuum as low as you can and then closing the valves on your manifold. If it doesn’t hold vacuum then your expansion valve is malfunctioning and should be replaced. Honestly if I were the stealership tech I’d have replaced the compressor, dryer, and expansion valve or orifice tube and used the 23 ounces as a starting point.
On a running system I always add to the low side but if the system is vacuumed out I’m turning the can upside down and dumping liquid into the high side. I’m to impatient to bring it from zero on the low side.
To vac the system you should open both the high and low valves on your gauges. Vac for an hour minimum then close off your valves. Your vac reading should maintain for a minimum of 45 minutes to ensure there isn't. any leaks. Purge your freon line then open the low valve only (the high valve shouldn't be touched throughout the rest of the filling process). When doing the initial fill with the engine off (that's the way I do it) , notice the gauge readings once it levels off.........the high and low readings should be exact or close which indicates a proper set for the expansion valve........in other words it should be functioning. Start the engine, a/c on, high blower speed with recirc on if you have that. 1500 rpm is good for filling. Check the ambient temp according to a chart, then crack open your low valve and let the system take freon in 50 psi increments (again, this is the way I do it) waiting a few minutes between 50 psi charges. Watch your vent temp........ideal is 35-45 degrees which in a mini you won't get. Get the high side to the reading on the chart......it should be around 7 times the low reading.....in other words, if the low is 30 psi, the high should be around 210 psi on an average system. Look for a vent temp within the specked range. This is basic steps; I haven't used a measured load for 30 years...........it's a feel thing for me. There is always a system that just has to be different and out of the normal. Before you even start this, you really need to pinch off the water flow to your heater core FIRST. The shutoff valves are usually crap and don't seal worth a dam. Even slight flow through the valve to the heater core can make a 10–15-degree difference in your air temp.
I've not seen anybody mention "superheat", nor "subcooling" which can readily determine the efficiency of the coils and interpreted correctly, the overall system operation. "Superheat" measurement will determine the efficiency of the evaporator coil, "Subcooling" does the same for the condenser coil. Both must be clean and both must have adequate airflow across them for proper operation. VeTech63 has given the best advice I've seen as far as "generic" information, but true superheat and subcooling measurements are universal and have definitive numbers for any mechanical cooling system.
You can see from reading this that there’s a bunch of different ways to go about it and that pressures are more indicative than absolute. This is the kind of stuff that drives a lot of people absolutely nuts, including me, when working on AC systems.
In the minis I have seen, the condenser is way undersized in my opinion. It's rare I can get to a good vent temp because there just isn't enough temp drop across a small condenser. Since the OP's machine is new and under warranty from what I understand, I'm wondering if the issue is bleed through from the heater core or a lack of airflow through the condenser. The bad thing is.....by screwing with it under warranty as a consumer, there is a chance the dealer can deny warranty if the owner creates a problem with the a/c system. Right now you're damned if you do, and damned if you don't. You have to pick your poison here. A quick check on a condenser cooling problem..........spray it with water while your a/c is running............the temp will go down with the high pressure in this scenario if the airflow through the condenser isn't enough.
I mentioned subcooling in post #25. That is the way to do it for a TXV system, if the condenser is big enough to actually subcool. If it's inadequate, you can end up dumping more and more refrigerant until the high side gets too high and the compressor is overworked. But high side does not seem too high on this system, so my guess is that it needs more, but that is only a guess.
You need to brake down and pay a guy that knows his stuff to look at it stop trying to get it fixed for free. Ask around and find some ac guru maybe even a hvac guy. The dealer is hoping you will get tiered and go away.
If it's a warranty issue and the dealer doesn't have techs. experienced enough to fix it, they should be the ones paying to have it taken somewhere that knows what they're doing. No way the owner of a new machine with only 100 hours should have to pay $100/hr.+ to fix what should be a warranty issue.
You did mention subcooling and I negated the input as you did not include anything else. We know subcooling and superheat play hand in hand and an undersized, or inefficient coil, (condenser) will drive compressor discharge pressure up, increasing workload on the driving motive, with negative effects on superheat. Too little superheat, (flooding of the evaporator coil) or too much superheat, (evaporator starving or undercharged system, or lack of adequate airflow across the coil) equate to the same result; customer complaint(s). Condenser subcooling sets up the inlet path for superheating to take place in a closed loop system such as mechanical refrigeration. I'm not going to add a lot to confuse or lose track of the OP's concerns, but I feel he is victim of another "Franchised Box Swapping Ape Show" because what has been posted so far indicates the servicing "technicians" are lost in the problem. He should find another dealer since this is a warranty scenario. OEM customer service will sometimes authorize this very easily. We all do things different to achieve the same favorable result. Hopefully this scenario plays out well and all will be good.
The problem now is that there isn't many knowledgeable mechanics left. It's nothing but part's changers in dealerships now. If the manual doesn't tell you what's wrong with it then there's nothing wrong with it.
OP here again. I appreciate everyone's help. I am planning to try talking to the service dept. again and probably the salesman. It took me about 10 minutes of arguing with him to get the service guy to agree to even look at it the second time, so I assume this time won't be any better. I do like the idea of them authorizing it to be serviced at another Bobcat dealer. I will bring that up. I think they are blowing me off because I am not a contractor with a bunch of machines, could be wrong. When they looked at it the second time they said there was a clogged drain line and they fixed it and everything is fine. I used the machine for a few hours the other day and after about a half hour or so I noticed a little water coming out of a couple of the vents. I looked at the drain tubes and 1 of them was missing the rubber drain valve at the end of the tube. I assume it's sucking in air from there and it's getting into the vents now. Also, with the machine running there is none, or very little water coming out of the drains. As soon as I turn the ac off, a lot of water comes out of the drains.
sounds like it is icing up the evap core has the thermostat been checked, does it even have one?
If the evap is icing up, then cooling will be poor, and refrigerant flow will be low leading to low pressures on the system. Might be on to something there. There should be a switch that disengages the compressor clutch on low evap temp or low suction side pressure or something like that. One way to prove this scenario is to run the blower on high all the time and engage the AC only some of the time in order to keep the water thawed out. If the controls will let you do that. If you switch off the cooling and keep the blower on high and a whole lot of melt water runs out, so much more proof to the problem.
Chances are the water droplets coming out of the vents are being blown off the evaporator coil by the blower motor because the airbox is not draining the condensate water out. If you have condensate water, the evaporator is not freezing, (usually). You mentioned these drain tubes were clogged. This can be for a couple of reasons but I don't know your system or design so can only go with educated guesses. If you have a selection of recirculated air, or outside air, (as automobiles do) using outside air will quickly plug or foul filters and the airbox drains as this type equipment doesn't typically reside in the a clean environment. If this case use recirculating air only. If there is a filter in the system, it will be prior to the blower motor. Ensure this is clean and stays that way. Either no filter, or a clogged filter will eventually dump what it cannot hold into the airbox and this could clog your drains. Those rubber "Vacuator" tips on the airbox drains do a good job of letting the water out and disallowing dust and dirt in when they are new. As they age they tend to not perform quite as well. This should be no affect on your machine citing age yet. Another scenario I've seen a couple of times in the automotive world is the foam strips that separate the heater core from the evaporator core section(s) either misplaced during assembly, or rotting apart from age clogging the drains. This can also allow heated air which is blown through the airbox to escape over into the evaporator compartment warming your discharge air. Not so much of an issue with the heater operation as you don't run the heater and air conditioner at the same time during the colder months. As far as condensate water escaping faster from the drains when the system is shut down is usually a pressurization problem in the ducting meaning restricted airflow through them. The water is probably "pooling" someplace and when the blower motor is not running the path to drain is less restrictive. That is just a guess however. The root problem here is usually dirt or something fouling the discharge path. Compressed air blown back through the drains will temporarily remove a clog and sometimes clear it, but a short burst of air only as you don't need to blow anything up.....
Your exactly right but thats not the way things work alot of the time. I would be in jail if i bought something new and couldnt get them to fix it. If they didnt want to fix this i would get a sheet of ply wood and paint a sign telling what was going on and park the machine as close to the dealer as i could. The way a warranty works from what i have learned is the customer has a problem the item if cheap gets replaced or money refunded . If is a big item they try to repair it if that dosent work they try to stall till the warranty runs out. My brother bought a used car it wasnt very old and had a warranty before the warranty was up he started hearing a noise he keep taking it back warranty runs out trans gos out . Turns out this car was known for trans problems what do you think was going on the dealer had to know these cars had a trans problem and the noise was something to do with that.
You bought a new machine for 10's of thousands of dollars. The AC doesn't work. The dealer fixes it or authorizes someone else to fix. If the dealer won't do that you contact Bobcat directly. Reference to a used car is apples and oranges. If your brother could prove they knew about the trans. problems, he could sue them for gross negligence. In your case it's a brand new machine and everybody is fully aware of the problem. They can't stall till the warranty runs out. You could say it's too unbearable to work in and ask for another machine or your money back. The dealer and/or the OEM need to to fix it for you. You shouldn't have to get forceful but sometimes they force you to. What if the engine was the problem and the dealer couldn't fix it? It doesn't matter if you're a 1 machine operation. They need to fix it for you, that's why you have a warranty in the 1st place. Take them to task!
Good idea! Didn't occur to me to try that. So after running the machine until there was some water coming out of a vent, about 30-40 minutes I left the fan on high and turned off the ac. No extra water coming from the drains. At that time there was a slow drip out of the drain that still had the rubber valve on the end and nothing on the one they removed the valve from. As soon as I turned off the blower there was a lot of water coming out of the drains, especially the one they removed the valve from. Did the same test with the blower with the ac on and same results. Also, I kept track of the temps at the vents at different time periods. It was about 86 degrees and humidity was quite a bit lower than usual. Blower was on the highest setting. After running about 10 minutes the temp was about 47 degrees. That's the lowest I can remember seeing it. 20 minutes later the temp was about 60. 6 minutes later it was 64. 5 minutes later it was 55 and I first noticed some water coming out. After that I let the machine site at full throttle- in eco mode and watched the temps. They would fluctuate between 56 and 62 degrees. I have no idea what any of this means. Hoping somebody does.
You're absolutely right. I've been trying to be nice about the whole thing but that's getting me nowhere. I will give them 1 more opportunity to fix it before I go to Bobcat. Although the dealer claims there isn't a problem, lol. I think I'll talk with the salesman first before I talk to the service guy. The salesman is very aware that the main reason I bought the machine form them was because of concerns about service. I would of bought a Yanmar, which was considerably cheaper but the dealership was a small farm equipment dealer that has only been selling the Yanmars for 2 years. When I asked the Yanmar salesman about their mechanics training or experience working on them he wouldn't give me a straight answer.
According to the parts breakdown it does have a thermostat.
Here is all the data for my 322. 100F ambient, still pulling down. One snapshot at idle, another at WFO. TXV on these does run low pressures. Verified in the books because I didn't like it. However, she pulls on down to 'ball freeze' levels after a bit. I do work on HVAC obviously. Will help where I can here. If your ambient is 95F+, on a cold start (cab is hot as hell), you better be seeing head pressures over 200. I do agree with one poster is the charge removed SHOULD BE WEIGHED OUT! That is highly important to determine what is in it. That tells a huge story right there! You have 100hrs on the machine. I would not suspect a plugged anything! It is possible the compressor is ****. Pulling all the data like I have provided starts to paint the real picture of performance! Not trying to step on toes, but there is some pretty inaccurate advice in this thread! The issue with SH/SC in mobile systems is the huge variables of compressor speed and condenser airflow! It is valuable info, but these are moving targets! I know what I am looking for. I will be honest, my system could use a few more oz.... but I am rolling it. F it!
How are you getting the MVAC quick connectors into what I presume are the standard refrigeration connectors of that test kit?
They do make adapters for this biz..... I run them, and I like them.....
In both of these deals if every one has proof that they have a problem and tryed to get it fixed then at the end of the day they could get a lawyer and try to sue but i dont know what he gave for the car it could have easly been worth alot if it was only a year old. But going to court the good guy dosent always come out the winner. I have been there before and court isnt always about write and wrong its who is lucky and has a good lawyer. I have made alot of mistakes in my life and its easy to point out when others make mistakes my brother made a mistake and Doug5801 has to they should have never left the lot until they thought the problem was fixed.
To hell with trying to get them to fix it. The amount of down time , I would just put the new thermostat switch in it and move on. I thing this thread has let you know what is wrong with it. The ac cools till the core freezes. Then will work agaiin briefly after it melts. If you could see the evaporator corre when it quits cooling it would look like a block of ice , not just frost. The thermostat typically has a capillary tube that stick in the fins of the evaporator. It cuts the compressure off to keep the core from freezing.
I will assume the machine is at the dealer at this point. What they need to do is contact Bobcat and triple verify the charge amount for the system. I know they are going to look it up and weigh in exactly that much. That is the extent of their experience! All indications I see so far is either a bad compressor, or possibly just low charge. In cases where head pressure is low and suction is normal-ish, it would be prudent to add refrigerant to see if head pressure climbs. These systems are sensitive to charge so it should not take much to affect some change. What should be checked is the subcool on the liquid line, which will further confirm there is a big problem. That unit will run with an H valve TXV and liquid receiver/dryer. We check the subcool to ensure we are getting nothing but liquid to the TXV. If there is little or no subcooling, we know there is gas going to the TXV, and that will not work. We run higher head pressures in mobile to 'force' subcooling. Since the vaporization temperature is relative to the temp, and the temps run quite hot, we have to run head pressures up to ensure we have liquid to the TXV. For a few reasons, I am doubting the icing theory. If head pressure is low, subcool will be low, so capacity is not even there to ice up. as well, the system will run a temp sensor at the evap as well as a suction line pressure sensor, both working to ensure it does not ice up. I am sure Bobcat (if they understood anything) could plug in and simply review the temp sensor value. That value would be largely helpful. Remember that these systems are designed to cycle on and off and it is part of the design to run evap temps down near freezing before cycling the compressor. If the temp sensor was bad, I would think a code would be present as the system will also be looking at other values and determine its state. The other possible scenario is a faulty TXV that is overfeeding. I am doubting that because if it was bad enough to drop head pressure that much, suction side would likely be higher. Oh, I should mention that I am going off the low head pressure for guidance. That aside, the first thing I would do is find the fresh air cabin filter bay and plug it with a plastic sheet. I have seen this before where people are chasing their tail with AC temps, they are in recirc mode, but guess what? That damper no worky! You won't get cold air without recirc.
I think before I dove too deep into it, I would be checking vent temps of other machines that are new or newly new to make sure that's just not how they are. While it may not seem good enough, if that's how they are made your issue isn't with the dealer at all.
I agree after hearing about the water dripping/blowing while it's running, it may not be icing. Usually when it's icing, it will just continue to freeze until shut off. I did have a KW one time that would work fine most of the time and suddenly decide to ice up completely, and then half an hour later finally cut off the compressor leading to fogging the windshield and a lake of water. Usually that happened in winter, though. We never did figure that one out nor could the KW dealer.
Before the machine was brought in the first time, I added about 8oz. of refrigerant to it. It made no change to the pressure readings.
The first machine was sent back without anyone contacting me. On the second service I told them I wanted to talk to them before sending the machine back. Talked to the service guy and he said they found a clogged drain, did a few other things and it's working better now. I asked him about the pressure readings and he said they were normal now.
The thermostat on this machine is an "electronic deicing thermostat". I would be fine replacing it but it's tucked away in a hard to get to place and the service manual says to make sure to reinstall it in the same location or it could effect the ac performance. Unfortunately the manual has a crappy little black and white picture that is no help regarding the exact location.
I want to say thank you to everyone here taking the time to help. Thanks to you guys I can sound a little more intelligent when I talk to the dealer. You've definitely put in more effort than them. I talked to service yesterday. They are going to look at the machine again next week. They said that they did remove the valve at the end of 1 of the drain tubes because they are prone to clogging. They also drained and refilled the freon with dye in it to check for leaks. I asked him if they checked the thermostat or the expansion valve or the compressor. Answer is no because they didn't throw any codes. I did a quick search of all the codes listed in the service manual and didn't see any relating to the any of them. I'll check again to be sure. He said that when they sent it back last time it would get down to about 54 degrees at the vent. He also said that they have a brand new machine there that they checked and that it only got down to 50. I said I have a new machine too and it's closer to 60 and the pressures are still off from the service manual. I said that they should start replacing some components if the can't get it to work right. Also told him that the last time I ran it, over a 45 minute period the vent temps varied between 48 and 64 degrees at max fan and coldest setting. After that point it was more consistent and stayed between 58 and 62 and that after a while water starts coming out of a couple of the vents. Also told him that I checked the air temperature inside the machine on the opposite side of the vents. When it was 85 degrees out the best the machine could do was about 82 inside. When it was 95 out, it was a little over 90 degrees inside. He said that he has been in contact with Bobcat about it and opened up a case during the last service about it.
I made a post on the compact excavators forum trying to find someone with a machine that could check his temps but haven't heard from anyone yet. My wife contacted some youtube guy who has a bobcat and lives in the general area. She didn't ask about vent temps, but the guy said that the machine's ac has no problem keeping it comfortable in hot temps.
I do realize, which is why one of my thoughts was a compressor issue. I personally don't see them actually bad very often unless people have been in the system. Amazing how that works! They have now been in it now. I am not really convinced it is bad, but data is pointing me there. I hope you read what I posted earlier. It will probably do little good as I bet the techs don't even know what subcooling is. I am just frustrated FOR you.... The reality is I could be connected to that system and collecting all the vitals at the OEM spec charge. Then add and monitor my values. I think the dealer is scared to add refrigerant because they don't understand them, and I am still sort of wondering if that little guy needs more juice. One thing you said is vent temp hunts around. That is an indication of compressor cycling or low refrigerant typically as the TXV will hunt around based on what it is being fed. If you want something very simple to check, if it is super hot both inside and outside the machine and you run that AC, see if the compressor cycles (clutch kicks out). It should NOT. At some point.... Looking at the head pressure, say it is holding at 170, add a full 12oz can of juice! If it can take that and the head pressure does not budge, time to look real hard at that compressor. Some of them have an internal relief valve to keep from being a grenade, and possible that is bad.
It sounds like someone at the dealer is trying to help you, maybe the service manager, but on the other hand someone is trying to blow you off, maybe the manager? It was brought up in another thread a while ago that some dealers don't like to do warranty work because it doesn't pay as much as regular service work.
So, you added 8oz to a 30oz system on a 100hr machine? You added 25% more refrigerant and the gauges still read the same? Something's rotten in Denmark here...as I've never added and not seen at least a miniscule change in pressure on at least the high side. And, most certainly, on the static pressure.
Thanks, I did read your earlier posts. Can't say that I understand them, lol but I will ask them about subcoling. I will check for the cycling when it gets hot out again. I have a 1 minute video on my phone of the gauges after I got the machine back the second time showing the pressures and it cycling once. Haven't been able to figure out how to post it. Also don't know if that would help make a diagnosis or not.
It's the same person, the service manager. The first time the machine went in the communication was through the salesman and that caused some miscommunication. He is the one who is bringing the machine back and forth to the dealer. I was expecting to talk to the service guy before they brought the machine back, but it was brought back without contacting me. I called him before it was brought in the second time. I had to discuss/argue with him for about 10 minutes before he agreed to look at it again. Didn't need to argue with him yesterday about them looking at it again, but I think we both still have different ideas of what outcome is acceptable.
I'm 99% sure they won't understand subcool, and it is just another diagnostic tool. This is why I am trying to revert back to other ways to find the issue. You can just explain what the gauges did in your vid. Was the head pressure stable? What was it? What was suction doing? Dropping, stable? What pressure?
Yup, the system actually calls for a little less. 1.7lbs or 27.2 oz. I asked the service guy about this and he had no answer, except to tell me that I shouldn't of added any and that I could damage the compressor.
Pressures were very steady at 20 and about 160. I'm not sure how long they were steady before the compressor kicked on but it was at least 20 seconds. Then the low side went up to about 48 and the high side down to about 110 and the compressor kicked back on and the low side went to about 20 again and the high side to about 175. I did this video on the day I got the machine back the second time so I didn't time to see how long between cycles.
If your outdoor temp was 95 or above, you should have had head pressures similar to my first post here with pics of my system data. My experience is leading me to low charge or bad compressor. The more data that is collected, the easier to pinpoint the issue! As well, you really need to check the drive belt for the compressor to rule that out. If it has an auto tensioner, that's a quick deal. Another check is to see if there is response between idle and full throttle on head pressure. There should be, the pump is running faster. If not, that is more intel. I'd like to know what compressor it has. Make and model.
I think the temperature was in the mid 80's when I took the video. One thing that I have noticed is that there is very little , if any difference in the high or low pressures whether it is checked at 80 or 95 degrees. I will check and verify that in the next few days. I will also check for the differences at idle and full throttle. There is an auto tensioner on the belt.
I can't see much of the compressor but it is a model no. QP1812 and maybe the brand is TCCI?
http://www.valeocompressors.com/media/brochures/TM08-16_servicemanual.pdf You might try to confirm, but it appears the TM13 might be common for Bobcat. Review pg 10, part 26, relief valve. If I am right, block all airflow to the condenser with cardboard while monitoring head pressure. Even better if it is 95F+ outside. If head pressure refuses to increase, a compressor issue is likely. Again....man, I would want to monitor subcool here, or more importantly, the liquid line temp because that can be very telling.
OK, try to bear with me. I'm trying to understand what you're saying. I know that the low pressure is the suction line and the high pressure is the liquid line. Where do I check the temperatures at? By the connectors where I hook up the gauges?
The line temp would be measured after the condenser. There will be lines going into/out of the receiver. That is a good place to gather the temps. I prefer after the receiver as it gets me real world data going to the TXV. if you reference my image, you will see my line temp was about 126F, and ambient was 100F. Do NOT test with a stupid IR gun. You need a good thermocouple ziptied to the liquid line. You would read the temp at the same time as the pressure. Subcool can then be calculated from there.
I did the tests. I checked the readings every 5 minutes or so. I'll give you some of the data and if you need more I might have it. Unfortunately I can't say that I'm 100% sure about the liquid line temps. I got almost the same readings from a very good digital meat thermometer and I used an infrared too just to compare. Either way, it was warm to the touch at the drier but not hot. Highest reading I got was 110. After re-reading what you said, I thought that I was supposed to check after the drier where there isn't any room to hook up a probe. I think you're saying that it can be before the drier. I can try again tomorrow. Both the low and high pressures generally varied by a few psi every few seconds each cycle so I am giving the middle numbers. At startup the outside temp was 93 and it was 139 inside the machine. For the first couple of minutes, the low pressure was about 28psi and high was about 200psi. After 15 minutes the low was 21psi, high 178psi, vent temp 54, liquid line 110 After about 18 minutes the compressor turned off for the first time. After that it cycled every minute or so. After 25 minutes low 20psi, high 175 psi, vent 55, liq line 109 After 45 minutes low 19psi, high 163 psi, vent 50-but quickly went up to 58 while cycling, liq line 108. There was very little water dripping out of the 2 drains that I can see. There is 1 drain that I can't see. The one that still has the valve on it drips about every 14 seconds. I did not see any water coming out of the drain with the missing valve until I turned off the blower and a lot of water came out immediately. Also, by the end there was water coming out of a couple of the vents again. Hope all of this means something and let me know if I need to do some more tests. Thanks
Well documented! I have to get to a 'thing' right now, but I will review all the data. You did a good job and this should help. If your cab was not cool, that compressor should not be cycling. I don't like it's pressures but it does have some subcooling. As for the water, I think it is unrelated and there is a drip pan inside and I think the tubes are projected up, not flush with the bottom of the pan, so the pan can hold water. this may explain no water coming from unit, and water in the vents as the water level comes up where the blower fins can contact it. Either way, it seems pretty obvious that the cover of the unit in the cab has to come off the figure that one out. may find other issues there as well. I want to know why it is cycling.
That "no dripping until I shut it off" deal happens on my 908M as well. Started at hour 1, now a year and 280 later same thing. I just assumed that it had something to do with the "pressurized cab" nature of design. The cooling performance is adequate, so the system pressures have not been checked. This same basic cab runs on all CAT small wheel loaders over the last 10 years, so if the "hold it till you shut 'er down" condensate feature was much of a problem, I'm sure we would have seen it here?
I did some more testing today. First in the morning when it was about 80 degrees. Let me know if you want any of that info. It first started cycling after about 3 minutes and then kept cycling about every 70 seconds. Testing done at 94 degrees. 125 degrees inside the cab. I put a thermometer on a wire and hung it at about head height in the cab to test the cab temps. It didn't cycle for the first time until after running 77 minutes. After it cycled the first time the next cycles occurred at these intervals: 6:45, 5:30. 1:47, 5:40, 2:48, 4:55, 3:45, 1:48, 5:40, 5:50 and 3:17 After 5 minutes running full throttle. Low pres. 24, High 195, vent 61, Liquid Line 114, cab 92 After 15 minutes Low 22, High 190, Vent 54, LL 111, cab 84 After 40 minutes-fairly consistent. Low fluctuates between 19-22, High 180-185, vent slowly got down to about 50, LL 109-112, Cab 74 After 55 minutes turned engine down to idle for about 20 minutes. Low 30-31, High 206-208, LL 117-119, Cab 76 Turned back up to full throttle. Started cycling after about 3-4 minutes. Averages over the next 45 minutes or so: Low, 20-23, High 185-195, Vent at beginning of cycle goes up to about 59, then down to about 50. LL 108-109, Cab 76 Hope this all means something. I was kind of surprised that there were better pressures at idle. They were much more consistent too, very little fluctuation. Thanks
Sorry man! I had some obligations this weekend. I am still reading through all the test data but everything I can see, it really looks like low charge!!! I will explain. 1. Head pressure lower than typical of MVAC 134 system at those ambient temps 2. Compressor cycling way before cabin temps are cooled down. 3. High vent temps indicating higher than normal evap temp 4. Not much condensate further indicating warmer evap. though it would be nice to know what the evap or suction line temp is running, everything so far would indicate the cycling is not being caused by low temps at the evap (freeze/etc), but low suction pressure. In almost all cases if you have low suction and liquid pressure, the system is undercharged! But how could that be when using the factory spec charge? I just don't know, I am just calling it like I see it. Because the clutch is computer controlled, it could be a HVAC glitch causing the cycling, but otherwise the system appears to be "close". IE, I see pressures and temps that I would consider in range for a good functioning system that just needs a little more charge. I am not saying "go charge it" just yet, just sharing what I see right now.
I looked at some of your values for liquid line temps. I do 'prefer' temps after the receiver, but gotta work with what ya got. Temp is not likely to be much different. I see subcool that initially was around 20*, but dropped to less than 10. In MVAC it is pretty normal to see 30* of subcooling. The way we achieve that is higher head pressure. Basically this is ensuring nothing but liquid goes to the TXV and the receiver you can consider a 'liquid reservoir' where liquid is on tap and read to go to the TXV. This is because of the variability of RPMs and inconsistent conditions. This is why subcooling is usually much higher than any stationary system. To be honest, I would be very surprised if you added 134 to this system and did not see anything change. I don't see anything yet that really confirms a bad compressor. The condensate issue needs to be addressed and it needs to be another test point to monitor. Part of the reason for AC is to remove humidity as latent heat so yeah, it should be puking water when running. If there is no or minimal condensate, I already know the evap is not getting much below dew point.
It appears that the problem isn't going to be easy to diagnose, which is probably why the dealer isn't fixing it. They seemed to be focusing on the refrigerant levels too. I know that you already addressed it, But I did add refrigerant before I brought it in the first time and it made no difference to the pressures. If they don't fix it again when it's brought in this week, I'll consider adding the 12 oz. like you suggested. Because at that point I will probably start replacing components myself. Starting with the thermostat and after that the expansion valve and compressor. Don't know what else to do. As far as the water coming out of the vents, that never happened until the machine was serviced the second time. I did get colder vent temps and slightly higher pressures after the second service also. If it will make a difference diagnosing the problem, I can look at the liquid line again and see if there's a way to check the temps after the receiver. Thanks for the help.
I am not as worried about testing after the receiver as I am getting accurate data. I see guys try to use a meat probe! You really want a good thermocouple firmly attached for accuracy. That is really just one data point though. I would not go in blindly replacing things. An underfeeding TXV will typically have low suction but high head pressure. You don't have that. When we talk about 'vent temps', you must realize we are looking more at the delta T across the evap. That is the difference in temp of air going in, and temp of air coming out. Perfectly normal to see higher vent temps when it is trying to pull down a hot cab, but vent temps should steadily decrease. It is also a function of airflow across the evap so if I want to see if I can get vent temp to drop, I will lower the fan speed. That 'should' drop vent temps at the sacrifice of air flow. If you can get access to the suction line close to the evap anywhere, it would be good to feel that. maybe it is possible air is bypassing the evap, which WILL cause low suction, cycling, etc, yet not get cold vent temps. Not likely, but..... this one is a brain bender. Don't ever blindly add 134 based on weight in this case. Add some, while weighing what you did, and monitor the system. 12oz really seems like a LOT, but honestly, if the system took it and head pressure does not budge, I'd be looking hard at the compressor. The system info does not really suggest a severe undercharged system, so I probably would not make it to 12oz unless I start seeing response in the system, which would be increased head pressure, and better performance in the cab. Water coming out of the vents has to be addressed. That is not normal! But really, this is practically a NEW machine!!! And if it can't even maintain a comfortable cabin temp, something is wrong. Tell them to give you a different machine. I would make them fix the problem! That should not be your burden.
I should reiterate that adding charge beyond what is specified is NOT typical, and I'd probably want to talk to the Bobcat engineering group to discuss. What can happen is a larger condenser, receiver, lineset, etc, could have been used, which would require a different charge, which 'maybe' was not documented. In any case, adding refrigerant is going into the wild and these systems cannot be charged looking for a fixed value like subcool. Won't happen because those values are moving targets! I don't think you tried this per my previous recommendation, but if you are hooked on again, put cardboard over the condenser and see if that causes head pressure to rise. You should see liquid line temp increase and head pressure. Also remember every time you hook on, you are losing refrigerant. I use smart probes so I don't have loss but most use gauges with hoses.
I agree, but first I have to get them to admit there is a problem. First time they sent it back when the vents were blowing 60 degrees, they said that was normal. In order to get them to look at it the second time I had to tell them what the service manual said, vent temps should be between 36 and 53. We'll see what happens this time. But if they don't/won't fix it I will contact Bobcat.
I will do this the next time I test.
Did I see you say that when the compressor cycles off, there was still a big difference in the 2 pressures?
Not 100% sure what you're asking. When the compressor cycles off, over about a 5 or 10 second period of time, the low pressure rises to about 46 and the high pressure falls to about 120 before the compressor kicks on. Once the compressor kicks back on again, the pressures are a few psi higher than the average for a few seconds and then they drift down a little and hold fairly steady. So, for example when the compressor kicks on, the low pressure might be 24-25 initially then it falls to around 20-22 and the high pressure goes from about 190 to about 185.
I think Mitch might have been trying to assess leakdown at the compressor. However the TXV in these does not fully shut off plus the receiver would null that test in any case. It is by design that when the compressor kicks off, refrigerant continues to circulate at some capacity. As the compressor cycles, pressure will start to equalize, SH will go up, evap temp will go up, until it cycles back on again. Doug, keep us in the loop. I'd love to be on this job. I love the ones people can't figure out. Easy ones are just too easy.....lol
I thought you said when you just walked up to the machine and the compressor was off, there was that much difference in pressure, thanks for clarifying that.
I did the cardboard over the condenser test. It was about 98 degrees out and humid. Heat index 116. Before the cardboard. Low pres. 24, High 197. This is after about 15 minutes with the gauges on. After 18 seconds, Low 28, High 300 After 45 seconds Low 30, High 350. Still slowly rising at this point, but I removed the cardboard. I didn't know how long to leave the cardboard on. Is this the results you were expecting? Also, I ran the machine for about 6 hours before doing the test. For the first hour or so, the vent temp averaged around 56. After that, by 930 or so I needed the blower on full and the vent temps varied from about 59 to 62. When I quit running the machine, around 330pm, the vent temp was pretty close to 60 and the cab temp was around 84.
HOLY ****!!!!! I guess I forgot to mention to just try to get the high pressure to climb to a normal pressure. I would have pulled it at 300! Oh well, nothing blew up I hope???? LOL What we know now is that compressor is likely good and that is another card towards "it needs more charge". It really seems odd so either the shop can't weigh a charge properly, the OEM has specified the wrong amount, or some other factor. With that info, I would feel more confident in adding some charge. Still pretty crazy that the amount could be wrong, so if you decided to go that route, remember to add, then wait, then add, then wait. When you get in a rush, you overcharge equipment. It can take several minutes for things to balance out.
Lol, oops. I didn't think about how high the pressure would go or how quickly once it was blocked. I think I will wait until the dealer works on the machine again before I try adding any refrigerant to it or replacing anything. They were supposed to look at it this week but now say it will be next week before they service it. Thanks
I was just in mine and remembered something. My system data tag is in kg. Maybe someone doesn't math real well? You might run the math on yours and confirm how much they are adding to see if it pencils out.
I’ve seen OEM tags wrong, OEM service info wrong, and machines go wrong (get out of calibration) One memorable machine I worked on listed 2.5 lbs on the tag, 3 lbs in one section of the manual, and 5.5 lbs in another section.
I will add that to my list of questions and things to check for them when they look at it next week. I don't know as much about ac's as most people here, but it seems that the symptoms all point to low freon levels. I was using the machine a couple days ago and it was in the low 80's out. After the first hour or so the vent temps would vary between about 50 and 60 degrees. So I had to keep changing the blower settings as it got warmer or colder inside. In any of my other machines I would of had the blower on the lowest setting and maybe adjust the temp control here and there. But with the bobcat it's always set on the coldest setting unless it's 70 outside.
Doug, did you get anywhere with this?
Nothing yet. They keep pushing off working on it. I think they are hoping to put it off until it cools off this fall and I won't need my ac, lol. Supposedly they are going to look at it next week. I'll let you know what happens when they work on it. My concern is that they are going to send it back again without fixing it again and say that it's fine. Thanks
Here is what I do with dealers and warranty. When they call and say it's done. I say send me over the warranty invoice. Read what they tested and what they found and what they did about it. If they did nothing tell them try again and actually do something this time. Then you don't have to bring it out and back or even waste a trip.
Are they giving you a loaner while you're waiting around for them to get to it?
Great advice. Planning on getting the paperwork. They gave me the paperwork the first time I sent it in. It pretty much said that 60 degrees out of the vent was normal. They sent the machine back without contacting me. On the second service I told them to call me before they sent it back. They said they fixed it by cutting off one of the drain valves that was plugged and didn't send any paperwork. I'm going to ask for the paperwork for the second visit as well as the next one.
Nope. The machine is a little better than it was initially. When it was in the mid 90's, it would be about 90 in the machine. Now it gets down to the mid 80's, which isn't comfortable but it is at least bearable. If they don't fix it this time I will ask about a loaner. I'm retired and using the machine on my property. If I was still in business I would of gotten a loaner. I've been trying to be accommodating as possible but that may of been a mistake.
Shouldn't matter. You probably paid more than a contractor too. Is your money not as good? If they have your machine and can't figure it, they should absolutely give a loaner. Your work is just as important to you.
Ya, I'm sure I paid more for my machine. As far as the loaner, that's not really been the issue. When they do "work" on the machine, it's only gone a day or so, but they send it back still not working properly. I'm planning on talking to the service guy before they bring it back and if I'm not satisfied, I'm gonna to talk to someone at Bobcat and see if they will do something.
Update on AC issues. The dealer picked up the machine last Thursday. They called Friday and said everything is working as it should. They said they were getting 48 degrees out of the vents and pressures were fine. I checked and it was 82 degrees out when they called. I told them that it should be at least 10 degrees colder and that I didn't want the machine back until they fixed it. I also asked about the water coming out of the vents. They said they didn't see any. I told him to give me a call before they plan to send it back and I wanted the paperwork for this visit and the last one. They dropped it off yesterday without calling me, of course. The salesman dropped it off. I asked for the paperwork and he said since they didn't replace anything there is no paperwork. Even though there was paperwork for the first time they worked on it and didn't replace anything. He said that they removed another one of the drain line valves. I asked about the water coming out of the vents and he said a little condensation is normal. Obviously I'm not happy. I told him I'd run the machine for a while and see if it's any better. It's worse. It was about 85 and humid out. I ran the machine about 20-30 minutes and the coldest the vents got were about 55 and there's way more water coming out of the vents now. Here's a link to a couple videos my wife put on youtube. https://www.youtube.com/channel/UC7oSP2nbXp-vsL9VCTymRYg Just got off the phone with Bobcat customer service. They said everything goes through the dealer. The only thing they can do is file a complaint, which seems worthless to me but I will do anyway. They did say that I can bring it to another dealer if I want, but now I'm going to have to pay transport to a dealer around 90 miles away.
This is horrible!!!! IMO, this is moving away from just fixing an air conditioner, and towards nailing a dealer to the wall!!!! If not already shared, I recommend you provide your dealer information so people can beware of these deadbeats!!! What is going to have to happen is open the air handler box!!!! Spitting water like that is NOT NORMAL!!!! Honestly, I highly question that they every checked any pressures, recharged, etc, nothing. There is no sense in a recharge until the water issue is investigated. What I would do? I would start calling OTHER dealers, talk directly with the dealership owners, until you find one that cares!!! They can likely get you an inside contact with Bobcat or transfer your info to the right people. Bobcat is BIG, but NOT big enough to blow off customers like that. Around here, CAT is king, but our dealership is what made that happen. I cuss them because they certainly miss some repairs, but they also have district guys that take customer service personal and WILL get to the bottom of an issue, where other steps fail. Unfortunately the way problems get solved anymore is making a lot of noise. I would NEVER settle for that BS! Bobcat needs to get involved.
Yeah horrible customer service to the point of telling the dealer you want a new machine. Get a loaner to compare how the AC works on a different new machine. BS everything goes through the dealer. That's just Bobcat passing the buck so they don't have to deal with it. They need to deal with it after all the trouble you've had with the dealer.
I don't know what all is involved when I file a complaint against the dealer. I am hoping that someone from corporate will talk to me, assuming they care. I sent a link to the videos to the dealer and am waiting to see if they will acknowledge that there is something wrong that needs to be fixed. If they don't get back to me by tomorrow I will file the complaint and start looking for another dealer to service it.
I brought up the fact that my new machine isn't working properly and if they aren't able to fix it they should replace it. Unfortunately they say it is fixed. Their words yesterday was that the machine is "within specs". The specs say that the air coming out of the vents should be between 36 and 53 degrees, so if they can get it to 53 degrees on an 80 degree day then it's within specs.
Did they provide some form of paperwork indicating what temp is within limits, instead of just throwing out a number? If the spec is 36-53 bring it on a really hot day, if it can't hit 53 it's out of spec by their own numbers. I would also email bobcat directly so it's not related and ask them what vent temp you can expect on a new machine as you are worried they might not have good enough a/c, don't tell them you have a machine with an issue, let them think you are considering buying one. Have they showed you another new machine to show it has the same vent temps? That would be a pretty easy thing to justify that it's working properly, if it actually was working properly. That water is totally not normal though, you shouldn't have water dripping out vents. I've never seen that on any a/c system ever.
I have the service manual and it states that the vent temps should be between 36 and 53 depending on the humidity. I told them this after they sent it back the first time and said the 60 degrees I was getting was fine. They said that there will only be a 20-25 degrees difference between the vents and outside temps. When I sent the machine back the second time I put a copy of the specs on the seat of the machine for them. As far as comparing the vent temps to another machine, they made it clear that when they checked the machine it was within their specs. Doesn't matter what another machine is.
It sounds like they don't have any service people that know much about air conditioning. You still risk getting your warranty voided if you attempt any work on this yourself. You're in a catch 22 right now.
I read through this thread last night and had to let it stew a bit on the burning inside my head. I do have a couple of questions and observations based on what little I've had to do for operator complaints about air conditioning. I'll play the levels advocate here for a minute or two. My first question is do you shut the door and all the windows while running the AC? Do you have it recirculating the air inside the cab. The reason I bring it up is because you keep getting water being blown out the vents. Water would be a normal occurrence in a humid and hot climate because cooling the air would drop the water out. Cool air won't hold as much water. But if you are recirculating the air in the cab, the air will get dryer over time and the water will go away. We had tremendous complaints about AC when the weather would warm up in this area. The reason would be obvious when we drove out and saw the machine from half a mile away. The front window and door was open along with the side window. The cab filters would be found to be plugged and the air mix door was stuck. The training for the operator was that fact that the AC unit only had the capacity to cool the cab, and not whole outdoors. Basically they had a choice, close things up or forget about the AC. I also keep seeing a reference to a TXV or what is known as a thermal expansion valve. I worked quite a bit with those kinds of valves when I was in the navy. We had huge chill water units and a couple of big freezers that used them. When I got out and started working with auto and equipment units like Red Dots and such, I found out that they didn't use TXVs. All they had was an orifice and the switching worked purely on pressure. I don't mean to be blunt but if I were the service manager and it was found that the compressor is working properly, the pressures are at specification, the evaporator and condensers are clean and the receiver dryer wasn't plugged, then there is nothing wrong with the system. The more likely issue is the interpretation of how the system is supposed to work. Interpretations and opinions are not a warranty issue.
John C pretty much covered my thoughts on the water in cab and the operational characteristics. Where I really get lost is that adding refrigerant made no change, good or bad. Heck, if I leave the fan clutch activated on my peterbilt, and the ac on while idling, on humid, hot days, water will actually condense on the dash panel and the hvac box itself. And, every modern mini machine, excavator, skidsteer, or compact track loader here has an hvac system with compromises that make them inefficient or slobbery, or weak on some days, and, we never, ever run the machines with the doors and windows closed. I'm not saying the ac is right, but, nowhere have I seen verification of the cutout temp on the anti-icing switch, nor am I familiar with how the hvac box is constructed. Cat puts unloader nipples in the large excavator HVAC drain tubes, that always clog with dirt buildup, so much so that I've removed them. Left clogged, water will come out the vents. And Takeuchi excavator hvac boxes have the blower so low in the housing that condensate can spit out the vents when working on slopes. One of my TB180FR machines (I has 4) has similar temperature issues, and I'll be replacing the anti-icing switch as soon as I feel like driving 4 hours to that empty (waiting in materials) jobsite.
Maybe it's a temp difference here but my Volvo 210 and my Deere 319 I can run with the door closed all day long without an issue, on the hottest of days the Deere a/c can't quite keep up but it's close. I can't say i've ever seen water come out the vents even with a/c on full for hours on end. However 90f is a really hot and really rare day here, generally cooler then that. My Takeuchi 153 a/c is completely useless, i've never even bothered with it, but it's also a 2006. If I was buying a 2022 i'd expect to be able to close everything up and the a/c keep the cab comfortable, I wouldn't buy any machine that wasn't capable of doing that. I don't think it's a lot to ask, a vehicle has been able to have a/c so cold at the hottest of days it'll freeze you out for over 20 years why can't equipment be capable of keeping the cab comfortable? The smaller machines have tiny cabs, it's not a lot of space to cool. The thing I don't get is, if the system is working fine, why wouldn't the dealer show him another machine so they can say "see it's working exactly the same as yours" and it would be case closed. One thing you could look into is tinting some of the windows. I tinted the rear one on my mini when it broke, it helps a bit. Could tint both side windows, i'd imagine it would help quite a bit.
Exactly. But since they won't honor the warranty it probably doesn't matter. Problem is that I have no idea what to do. Maybe I should start with replacing the thermostat, then the expansion valve and compressor.
Yes, the door and windows are closed. As far as the air recirculating, there is no switch for that but there is foam panel on the hvac side cover. This machine does use and expansion valve and they say that they checked it and it's working properly. If you go by the service manual, the vent temps and the compressor pressure is not within specs. In the videos I sent the link to the vent temp is about 55 at around 86 degrees outside. Specs are 36 to 53. I haven't checked the compressor pressures since I got it back this time but after the first service it was about 20 on the low side and 165 on the high side and the vents were at 60 degrees. After the second service at 98 degrees out, humid and running for over 30 minutes at full throttle the low averaged about 24 and the high 200. The pressures were better for the first few minutes, L-29 and H-225, that's probably what the dealer is going by. The service manual says that between 86 and 101 degrees the Low should be 15-33 and the High 210-265. There are times when the vent temps have gotten down to around 50, but they also seem to fluctuate at times between 50 and 58 or so. The vents didn't leak any water until after the second service. There is a lot more water now after the 3rd service. As far as I know, all they have done for service is hook it up to a machine and remove and put the freon back in. They also removed 1 drain valve on the second service and another one on the third service. I think they added dye to the system to check for leaks on the 2nd service.
Is there any chance the wrong type of refrigerant has been added to it ? Or would that make a difference it there was ?
One thing I will say about this machine is that the blower is very strong. Seems almost double of what my other machines are. The downside is that it needs to be on the highest setting if it's much over 80 degrees and humid out. And it blows water in my face and eyes. I'm pretty sure that there is no icing going on. There isn't a lot of water draining If I turn the ac off after running for hours.
As far as another machine, they said they do have another one there and it was blowing a few degrees colder than mine, but they also told me when they dropped it off that all machines are a little different and mine is within specs so they "can't" do anything. I mainly got this machine to use instead of a beaten up 1997 case 580. It's got a bent door on it with a big air gap in it and the cab is probably 3 times the size of the mini and it cools better than the mini.
Do you mean when I added to it? I'm 100% sure I added the right refrigerant, R-134a.
Yes and no. The dealership also. They may have used recycled crap. Out of desperation I would drain it, do a good vacuum on it and put the correct refrigerant back in, with the exact amount specified in the service manual.
Does your machine have climate control? Can you set the temp on a panel that the system will try to maintain?
With a TXV system, the anti-icing switch is what cycles the compressor, well, to prevent icing. But, it is also the main regulation of the evaporator temperature. On my TB180FR that has underwhelming AC performance, the anti-icing switch is cutting out the compressor long before the evaporator is anywhere near cold enough. Jumper the switch and it'll go 40° vent temps on a 90° day, until it ices over, which is usually less than an hour, if it's any kind of humid out.
Read back through all that I have put into this thread! I won't retype it. You seem to want to just "change parts", convinced that will solve something. What are you fixing? You don't know! You are also fixated on "vent temps", and I already covered how that mentality is flawed. Either add charge under careful monitoring of temps, pressures, and ounces of charge, or take my other route and blow up the phone! If I need in, and someone won't open the front door, I will go to the back door, then windows, then kick in a door. As I mentioned, the water issue is separate and should absolutely be the focus of any dealer convos because it is NOT NORMAL!!! It will require that the AC unit in the cab be opened to expose the evap coil and condensate drain system. It is only then that you will find what is going on. Send your videos to Bobcat, and say, "is this what you call a quality machine??? You didn't provide goggles with my new machine delivery" You also have a heater core in there and someone already mentioned to ensure that is not causing issues. All you have to do is pinch off the lines to it somewhere, actually just one and it will stop any flow to it, and see if things improve. No need to replace anything.
Your asking for compressor damage doing stuff like that! part of the reason to cut out the compressor is to ensure there is enough superheat to protect the compressor. A TXV is specifically trying to achieve constant superheat. But I realize in many industries, the motto is "it's fine.....until it isn't".
Agree with others, do not just start replacing parts. They will void your warranty on it, and blame the issue on you. And it's unlikely to fix the issue. If you want to spend money on anything, get an experienced a/c guy to look at the system to see if he notices any issues and get his thoughts on how it preforms. I would also be hounding bobcat to do something better. One machine to the next if exactly the same should be very similar.
The bypassing is/ was done while testing only on my TB180FR while the hvac was opened for cleaning. But, I have encountered it several times where the anti-icing switch remained closed on my Kenworth W900 trucks (at least 5 times) and I still haven't replaced any of the compressors.
Might be worth a try. It is interesting that each time it was serviced, they said they removed and put the freon back in with their machine and each time I got it back the ac worked differently.
No climate control
Their AC machine’s scale and charging system could be on the fritz as well. I know ours is a 20 year old piece of crap that has to be worked on yearly
I know I am fixated on vent temps and pressures. That is the only argument I can use with the dealer to try to get them to fix it since those specs are in the service manual. If I do replace the freon as Tinkerer suggested I will first add some to see if it makes a difference this time. I did email the link to the videos to the dealer. Not surprisingly no reply. My wife contacted Bobcat on Facebook today and sent them the videos. They replied and said that someone will contact me. Trying not to get my hopes up, lol. I didn't crimp the hoses to the heater core, but I did check the temperature of it with the machine running for a while and it was about the same temp as the surrounding area.
I was thinking about hiring someone to check out the ac system. I've been happy with my Case dealer and might call them to see if they would diagnose it.
That would be pure GOLD!!! While it is at the Case dealership, make sure to snap a few pics, post them on Bobcat's FB page saying, "this is how good Bobcat stands behind their product. The guys at Case are a little smarter, they will figure it out"........ Seriously, I would TOTALLY blast their FB page!!! Before they can even take it down, thousands will see it. Unfortunately this is how anything gets done anymore. Internet blasts.......
I'm guessing then that your system is either on or off? If that is the case, there is no TXV.
Lol, that's a great idea!
Yes, it is an on/off system.
I'm confused...Could you clarify that?
A thermal expansion valve is used in a system where you set the temperature you want the cab to be at. The expansion valve opens or closes allowing more or less fluid to the evaporator as the temperature changes. You have a monitor panel that shows a degree reading that you can turn higher or lower which adjusted the expansion valve. Most of the little machines are either on or off. No TXV, just an orifice that passes a set amount of liquid to the evaporator all the time and a pressure switch that turns the compressor on when the pressure goes below a set point. That's at least how they used to be. School me if they are different now.
What I called the anti-icing switch is really a thermostat.
John, experience is something you have, but I think we covered the TXV matter several pages up in this whole mess. I hope I can help a little here. A TXV as you might know them has precisely zero way to be 'controlled' by anything other than temperature. This is quite different from the most modern EEV, which actually is electronically controlled. A TXV in a mobile system is typically called an "H valve"and has no external bulb on it. It snags the suction temp from damn near where the gas enters. TXVs are are insanely common today in mobile systems because they add a new layer of adaptation to conditions. This is all done in the valve and nothing any controller can do about it. It is simply a spring, needle valve, and proprietary gas on the power head side to drive the valve. If the gas heats up, it expands, opening the valve more. When things cool off, the valve closes down. I can tell you with 101% confidence my older CAT excavator has an Hvalve or TXV. I still have the rear trim removed and look right at it when I hop in the cab. It would be extremely rare for suction pressures to run so low without an TXV. They are able to exploit more capacity in a system. For that reason alone, they are common. As for having "climate control", whatever that means, that is not likely to have much bearings as a TXV is very much more adaptive making it a better solution for an "on/off" type deal. A/C is never on/off, it is always in a state of establishing balance. This is due to the receiver and variable compressor RPM.
The purpose of the TXV is to make sure the evap stays only 90% full (just throwing a number) and completely vaporizes the liquid before allowing it to return as vapor to the compressor. It does this by comparing the temp of the returning vapor to the pressure inside the evap and opens or closes the liquid feed line by degrees to maintain what it wants to see. As evap temp gets lower and lower it will begin to get below freezing point. The TXV does not know or care about freezing, so there is another thermostatic switch that turns off the compressor clutch if this happens to cause the evap to stay above the freezing point. This switch only comes into play when the cab is already cooled down and the operator has begun to turn down the air flow so there is not as much heat load on the evap core. Some cars also had variable displacement compressors or other fancy valves to do this in another way to regulate evap pressure, but I think the simple H-block and thermostatic switch was most commonly used the last 20+ years, until somebody came along and noticed there were no electronics and decided everything needs to have electronics and leave nothing un-electronified.
Please post a diagram of the system in the OP's subject machine. Also could use a diagram of a typical Cat, Deere or Komatsu system. That way we could all see where the components your are speaking of are located in the systems and understand how they work. The on or off I was referring to is the typical operating modes of the compressors. Push the button or flip the switch and the compressor will or will not operate.
https://shop.bobcat.com/6675534-a-c-valve-block This should cover a couple models......lol
That doesn't tell me anything about how it works. Everyone can see your expertise but the way you are conveying it is over most of our heads. Do you have a simple line drawing showing the system?
John, my "lol" was in reference to how many models are listed there, which I would conclude they use about the same system for about any cab. I don't have a schematic of the system in question in this thread, but I know how they work. The valve in that picture is a TXV/Hvalve/Hblock/metering device. The little disc on one end is called the "power head" that has a proprietary gas in it that will respond to suction like temps. On a stationary system, that 'hat' is usually connected to a tiny copper tube and "bulb" to sense the suction line temp. You will also see down one of the barrels there is the needle valve. There is a spring on that needle as well, that works in balance with the power head. It is 100% based on suction line temp. There is no way to control those any other way, and usually not even field adjustable, which limits some level of diagnostic in them. The TXV was ultimately designed to try to maintain "constant superheat". In a fixed orifice system, superheat will be all over the map, and largely underfeed the evaporator in a hot pulldown, thus high superheat. What needed to happen was the ability for a hot system to 'open up', allowing more refrigerant. However, if you run at full bore once things are cooled off, superheat drops to dangerous levels that risk liquid returning to the compressor. This is where the TXV would throttle down, limiting refrigerant to the evap, ensuring it all boils off and leaves with the proper amount of superheat. A ballpark is about 10* of superheat. But in any system, a TXV cannot fully shut off refrigerant flow as the compressor is still running. This is where temp and pressure switches come into play and if the suction line gets to a low point, it will cycle the compressor off. Due to the liquid receiver, refrigerant will still continue to flow, but at reduced pressure and thus the suction line temp will increase. This will then tell the AC control to kick the compressor back on. there are also low pressure cutouts on the suction which were common for orifice systems, but they still play a role in TXV because if that pressure is too low, that could mean low refrigerant charge, which could damage a compressor. Not sure if any of that helps in the clarity? https://www.mechanicalbooster.com/2017/12/car-air-conditioning-system.html Here is a link I found with a decent a simplified picture of how the TXV connects. What is unique about the mobile TXV device is the integrated sensing bulb that is reading the temperature of the suction line going back to the compressor. There are no outside controls for that device unless it is an EEV, which is not common for these.
What you are calling a TXV is working differently than what I have experienced. In a climate control system of yesteryear the bulb that controlled the output of gas to the evaporator was in the space where the cold air or chilled water was going too. In the freezer space the bulb was in the freezer itself. In the chill water systems the sensor was at a designated point in the chill water output. In old cars the sensor was in the car under the dash panel. In your explanation of the TXV I take it that it is a safety device to prevent liquid from getting back to the compressor. It really has nothing to do with controlling the temperature of the air coming through the evaporator. If that is the case, it is little different than a system with an orifice except that it might be safer for the compressor. I can't understand why it would have a bearing on the OP's problem nor how anyone could tell if it was working properly or not. Please explain the term super heat. I've heard some people use it but no one provided an understandable explanation of what it is and why anyone should care about it.
A TXV's purpose is actually to optimize system efficiency by being able to modulate refrigerant flow. It goes into a long explanation but as a byproduct of its function, it does give some protection for the compressor. In a fixed orifice system, you can actually watch the superheat drop, and it will drop all to way to 0, meaning liquid may enter the compressor. One of the fixes for this problem of yesterday was using an 'accumulator', which is basically a small tank on the vapor side, to give more time for refrigerant to boil and help prevent liquid death. As for superheat, I use water an an example because it is easier to understand it. Basically everyone 'thinks' water boils at 212F.....NOT! It boils at 212F at sea level atmospheric pressure. If we take water up in an airplane, the boiling point drops. As well, we pressurize engine cooling systems to increase the boiling point! As you increase the pressure of water, you will increase the boiling point where it turns to steam. This is precisely what refrigerant does, but at much lower pressures! So what is superheat? Superheat is the superheating of a gas beyond its boiling point. If you make steam at 212F, but you keep heating that steam to lets say 222F, congrats, you have 10* of superheated steam. In the refrigeration cycle, having superheat, means that your refrigerant being boiled in the evaporator has not only completely turned to vapor, but it has collected additional heat to 'ensure' it is full vapor. Technically you could run a system with only 1* of SH, but that is riding a dangerous line. But as with the water example, we see that water's boiling point is a function of its pressure. Refrigerant is the same. This is why you can never know the superheat without knowing the pressure it is running at. If you reference the pic I put in this thread I think, you will notice there are two pressures and two temperatures. Those values are used to calculate the superheat and subcooling of the refrigerant system. Those values are critical to properly diagnosing a system. Working with just pressures, you are only guessing.
John, you said freezer and chiller so I assume you are speaking of things like meat lockers. In yesteryear, those had fixed orifices because they were usually running under the same conditions all the time. The TXV is taking over those systems and home AC as well because it is more efficient (and complicated) like everything these days. The TXV feeds in the max allowable refrigerant to be safe for the compressor. It comes in handy like Fastline said because if it is real hot out and the refrigerant still has bubbles of vapor, it will open farther because those bubbles do you no good, they just pass on through. It always lets in the correct amount of liquid. They seldom have problems, but when they do, the whole system is screwed up. Almost everything uses some kind of TXV these days.
I was on a ship and water temperature and air temperature changed all the time. What you guys are telling me is that the technology and terminology has changed. So cab temps are exclusively controlled by means of an air mixing door in the evaporator unit. Is that correct. My next question then is how would you use superheat temperature to check and troubleshoot a problem? How would you even measure it? What would make you want to check it?
Everything has superheat. Aboard ship I am sure refrigeration techs checked superheat. Orifice systems are pretty hardy but you know they always want to make things more complicated. Automotive refrig systems have used TXV of one sort or another since the 50s. They were never exclusively fixed orifice, just 2 ways to skin the cat. Superheat is the number of degrees the return line is over the saturated liquid temperature at that pressure. https://learnmetrics.com/r134a-pt-chart-pressure-temperature-chart/ The evap is usually runs 90% full of liquid. Let's say it is running 30F. That is 26 psi. The liquid comes in the bottom and after it has a chance to flash off, all that liquid from bottom to top will be 30F. Once all the liquid is gone at the top, it is all vapor and that vapor gets superheated another 10F so now it is leaving at 40F. That way no liquid can be carried back. https://www.acservicetech.com/post/the-hvac-total-superheat-charging-method-explained
Have to disagree on this small matter. Running liquid in 90% of the evap would be a serious over feed issue, and be asking 10% of the coil to perform the magic. And that magic is the latent heat of vaporization. In short, no thermal magic happens until that liquid turns to a gas. It would be more typical to see a heavily loaded evap at 50% liquid, and lightly loaded down to around 20%. This state change can usually be caught on a FLIR camera.
This is from the service manual. I took the pics with my phone, if they aren't good enough I can have my wife make pdf files.
Oops, sorry. I'm about as good at adding files as I am understanding what you guys are talking about. Just meant to do thumbnails. Here's the last one.
The 90% was just a number I was throwing out there for illustration purposes. The technician has no way to know how much of the evap is liquid and how much is vapor. So long as the superheat number is correct, it should work as intended.
Birken: Thanks for the links and the references. They are a great aid in understanding what is supposed to be happening in a properly operating system. I can see now that just putting a set of gauges in the system might not be the whole answer to troubleshooting a problem. I very much doubt that any wrenches in the industry carry a chart that would let them know if the system is properly charged. fastline: It sounds like you work on these systems all the time and have developed your instincts and procedures for troubleshooting. I appreciate now that there is more to it than just plugging in gauges. Doug580l: Thanks for the diagram. It helps a lot by providing the graphic showing the metering valve and the bulb placed by the output of the evaporator. The diagram does not show it being connected to the vapor stream and instead indicates it is in the air stream monitoring temperature of the air through the evaporator. That is like the systems I am familiar with. Since the machine is new and under warranty you shouldn't be messing around with the system until you have no other choice. You may think you are there now. After making sure that you operate the system the way it was designed, cab closed and the cab air flow recirc is on. I would suggest that you run the machine in a test of actual system operation in the conditions that make the problems occur. Write down exactly what is happening and a time for each check you do. You may have to do this in front of the dealer salesman or service manager. Make the paper legible by typing it out if need be. I would next write out questions at the bottom of the test paper. You will need to convince a manager or factory rep that there is an issue and create doubt in people's minds that the troubleshooting was completely thorough. What was done when the technician checked the system operation? Gauges plugged in? What were the readings? Was the covers over the evaporator unit removed? Was the operation of any heated air door checked? Was the temperatures of the inlet and outlet to the evaporator checked? Were those readings checked for proper system charge? Was the unit tested when the ambient temperature was around 90 degrees? Were the drains removed and blown out to make sure there was no plugs? Last thing to bring up is that manufacturers very commonly assemble new machines with minor glitches. Perhaps there is some insulation covering a ducting connection. Maybe the evaporator is partially blocked. Maybe the bulb for the metering valve is covered or in the wrong place. All these things create some doubt in the manager's mind that possibly the technician didn't do a complete job of troubleshooting possibly because he wasn't fully trained. You might even consider finding a qualified outsider to check the system in the dealer's shop. If that person says its right then you pay, if he finds something wrong, then the dealer pays. I know it is a pain and you didn't buy a new machine to have to go through all this but it is unfortunately part of the process when things like this occur. Good Luck!
@John C. just for clarity, I wanted to point out that the book page 70-10-2 diagram provided by Doug is wrong! As is common in books that misprints happen, the diagram seems to show a separate TXV bulb connecting to the vapor line. that setup would be common in a stationary system, but is in fact wrong here, and even the plumbing is wrong. Figure 70-10-5 shows the correct TXV for this application. It can get really confusing when in the learning stage and get inaccurate material! The "thermostat" they show in that diagram is the temp switch, and they commonly stab them right into the evaporator fins to get the most accurate reading possible.
Excellent advice John, thank you. All very logical. I am having difficulty with logic lately by letting this bother me more than it should. It just pisses me off to spend that kind of money and then be lied to and ignored. I am waiting to see if Bobcat corporate responds. I doubt that I will get the dealer to agree to anything since they claim that everything is working as it should and it's been a fight to get them to look at it after the first time. The last time they looked at it they made me wait 3 weeks. They refuse to give me any paperwork for the last 2 services so it's hard to know what's been done already. Although something has been done the last 2 times because the ac acted different after each service. I am leaning toward bringing it to my Case dealer if they will work on it. Also considering selling it since I would never bring it to the dealer for service once the warranty is over. It may be some kind of glitch like you said. I never felt the ac was working right since I got the machine(March) but it became obvious as the outdoor temperatures rose. It's interesting that you stated to operate the machine in the conditions that make the problem occur. I was using it today and I noticed that it acts worse when the machine is being operated rather than just sitting at full throttle. I was trying to take more videos as the vent temps were fluctuating about 10 degrees (50-60 and later 53-63) while on the coldest setting and blower on high. When I would stop operating it and try to take a video it would only fluctuate a few degrees and generally be colder-52-54. When I was using the machine in the morning at around 78-80 degrees out, there was a lot of water coming out of 3 vents. Seemed like twice as much as the videos I posted. Then later in the afternoon when it was in the upper 80's there was much less water coming out of the vents but that's also when the vent temps were higher, up to 63 at some points. It may of been more humid in the morning.
A lot of people make the mistake of AC performance checks in cooler temps such as morning, in a shop under cover, etc. If you bring me a problematic AC unit I want to be testing it on a hot sunny day for maximum diagnostic reliability.
Got another video of ac. With the water blowing out of the vents I opened the cover to show the water inside. It was about 82 degrees out when we shot the video. Lots of water.
I am starting to smell something. I think a really good HVAC tech should look at this. What I suspect is possible air bypassing around the evaporator. Let me explain, if air is allowed to bypass the evap coil, it will give you ALL the symptoms you are experiencing. Low head pressure, cycling, high vent temps, etc. Basically you absolutely HAVE TO confirm that all the air moving through that system is being forced through the evap coil and the fact that you can so easily remove that cover and expose everything is eye opening! You NEED to look at how air gets sealed here. That is the first part. I honestly can't make heads/tails of the air movement and such here. It really appears that whole design is a mess. There should never be water all over the blower and electrics of a system. That thing will fail is short order! Keep at it! Send this crap all over the web and a guarantee you will force Bobcat to deal with it, and I would tell them to write you a 'special' check to remove the content. I have received exactly that when I exposed stuff like this. No way is that a good design!!!
My thought as well. I don't fully grasp air flow either on this one. Are we looking up down or sideways here? I have a dumb aftermarket AC in my old F250. It has a core that is much too small for the ductwork. It never worked until we sealed it off. In my case long outside of warranty. The old trick for air flow is to use the plastic foam pipe insulation in various sizes and stuff in the gaps. I like to smear with gorilla glue first so it stays where I put it. But also put it in snugly. Worked for me.
Wow, Starting to feel like it might actually get fixed now. What I don't understand is what they do at each service to make it worse. It never leaked any water before and after the first service, where they did nothing as far as I can tell. After the second service it started leaking a little water and did get colder. After the last service it's leaking a lot more water. I'll take a look at it and see if I can figure out how to check how the air is getting sealed. The cover is all plastic with no rubber etc to seal around the evaporator. I'm including a pic of the cover.
Here's a few pics of the system.
Looks like a lot of dirt has gotten in there. That evap core needs cleaned. Has the heater core lines been plugged off yet?
I checked the Bobcat parts site to see if maybe there is a gasket missing from the cover. It doesn't show one but it does list insulation tape, sold by the foot but doesn't indicate where it goes. It does show that there is supposed to be a specific insulating tape by the thermostat.
No, I'll try to do that today, fastline has suggested that several times. Very hard to see them. I assume if I find them I can carefully put a vice grip on them?
I did clean the evap core about 20-30 machine hours ago with compressed air. Is it normal for it to get so dirty so quickly? Is there another way top clean it?
You could locate one of the heater hose connections on the engine and install a ball valve to stop the hot coolant from going into the cab. I did it on both hoses in my backhoe and it made a big difference on hot days.
Good idea, ordered a couple from amazon.
Either something is missing or that is just a pathetic design, guaranteed to give you problems forever! This is a dirt machine. that intake for air should have a good and well sealed filter on it. If it doesn't make it that way! Why take it serious? Look at how quickly you are fouling the coils! You need to go around all 4 sides of the evap coils and either confirm they get sealed, or make them seal! A thick foam strip is probably what is needed on that plastic cover, even if the OEM never did it. Actually that whole panel needs a good seal, and it should both have a seal, AND be screwed into place. You can 100% bet air is going right around that evap. Whether this will solve anything with the water issue is not certain. the whole thing is confusing. Remember when I mentioned about checking the suction line temp???????? Yeah, problems like this would have been spotted a LOT sooner. If the evap is running super cold because of the short circuit of air, that could explain the wild condensate issues.
I crimped the heater hose by the heater valve and ran the machine for about 20 minutes. Didn't seem to make much of a difference. Vent temps were about the same and there was water coming out of them. I did notice that the compressor seemed to be cycling every minute or so.
I'll take a look at what I can see around the evep. coils. I may have to remove the dash in order to see the back of it. I think that I will put tape all around the cover to seal up any potential leaks from there and see if that makes a difference. We checked the evap coil temp when the cover was off. Think it would get to around 38 degrees or so. I did notice the coils get a little frost on them before the compressor would kick off and it would quickly melt off.
Not an AC expert but since that plastic cover has a coarse foam filter, it seems like everything else should be sealed so all the (intake) air has to go through that filter. On a vehicle if you don't clean the cabin filter you can take out your heater/AC motor because it's trying to work too hard to pull air through a clogged filter.
No, I don't think you quite understand! Yes that cover needs sealed well, but what keeps air from going right around that evap coil where that cover goes? That should have a seal on it. You would be putting foam on the end of the evap. I would shove a healthy strip between those copper Ubends that would engage the cover when it is installed. Think about this. The blower is pulling air on the left. Air will enter on the right of the coil. Any air leaks means air will go around the coil, not through it. As well, it is nearly impossible to test suction or evap temp with that cover off! there is no air going through it!
Just checked the machine again. Ran the machine about 20 minutes then pulled the hvac cover off. I thought I checked the heater core temp before but I must not of. With an infrared temp gun, the evap coils got as low as 29 degrees, but the heater core was between 60 and 62! And the heater core dropped a couple degrees after the ac was shut off. I assume that would cause most of my issues? I had vice grips on the heater hose by the heater valve but maybe it's not a good place or not stopping the flow. Hoping were closer to solving it now.
You might check where the heater hoses are connected to the engine block. Many manufacturers put shut off valves there.
If it's just a temperature control to regulate the flow to the heater it must not be fully closing off flow through the heater core. If it doesn't have a shut off valve should make a big difference adding one. My skid steer with a Kubota has a shut off valve mounted on the head at the flywheel end. a bit awkward to get at but it shuts flow off completely.
I mentioned it in post 7 on the first page. You must have missed that.
10 pages into this and it seems like nothing is getting fixed yet LOL. You more than likely have already hit the "No Warranty" part of this machine a/c by messing with it. It's time to start from the beginning............make sure you have gauges and a vacuum pump before we get started.
As mentioned, as soon as you remove that plastic cover, you just stopped all air from moving through the coils, so any testing with that cover off are NOT valid! As well, heat moving through the heater core would cause higher vent temps, but would not explain compressor cycling and lower head pressures. I strongly suggest getting even a good residential tech look at it to understand about getting those coils sealed better. I am convinced something is missing in there. Maybe a foam overlay inside that plastic cover.
10 pages of guess work, and the plot ALL changes with a simple picture. That is one shady setup! I really think an experienced HVAC pro should look at it. I don't find many mobile guys that know nearly enough to troubleshoot this. one of the very first things I mentioned is to ensure the evap is sealed properly. I got crickets. This is no different than trying to assess charge in a system when the evap is plugged!!! In both cases, a reduced heat load presented to the evap.
The other potential issue I see is it would see there is not a fresh air damper? IE, the filter opposite where the in-cab filter is does not appear to have a door on it? If that is the case, for this testing, go put some tape over that vent to block fresh air. That right there should be a dramatic change.
Ya I probably did miss that, and a lot of other things.
Not sure how to properly check to see that it's sealed. From what little I can see it is except maybe for the plastic cover. I turned the lights off and put a bright light on the side of the evaporator and could not see any light getting through to the heater core side. When I was using compressed air to clean the fins, it seemed that there wasn't much air coming out the other side, like 75% less. Don't know if that's normal or not.
Yes, getting close. Don't think I've done anything yet to void the warranty that the dealer isn't honoring.
Wouldn’t it be some crazy **** if you split the heater core and evap core apart and found a piece of cardboard or some shipping crap In between them from the factory? Assemblers do the damndest things…
I was thinking that too. Tried looking for something but can't see between the cores. Did stick a piece of paper between them and there was some suction. The cover was off but we put some cardboard in it's place to partially seal it up. I am considering removing them. I was also thinking maybe they used a different evap or heater core, blower or something else because of the supply chain issues.
Ensure this seals to this. We are not there to determine if things are actually sealing but without any foam there, I am certain a level of leaking is occuring. just moving hot air right on over to the vents. Also note arrow by evap. That is fresh air filter. BLOCK IT!!! All of this is guess work without knowing what the suction temp is! Simply tiptie a thermocouple to the suction tube seen in the pics, put cover on, run it, observe temp! It's critical data here!
OK, doing the testing now. It's only about 70 out so I don't know if I should wait and do the testing tomorrow. I'm not sure what you mean by suction tube. I have the thermometer in the compartment on the suction side. Do you want it ziptied to the side of the evaporator? Should I block the fresh air filter at this time? Machine is running now and the fresh air filter is blocked. Vent temps are around 45 degrees. Noticeably less air coming out of the vents. Water started coming out after 5 minutes or so. It comes out of the joints in the console before coming out of the vents.
Here's what I got from the testing. With the fresh air blocked, about 78 degrees in air intake compartment. Vents temp low about 47. Cycling often. Leaking water. Quite a bit less air flow form vents. After unblocking fresh air filter, got down to about 69 in the compartment. Vent temp low about 48. Leaking lots more water. The other intake filter is inside the side compartment next to the hydraulic tank, etc. Hyd fluid only got up to 100 degrees while testing. When using the machine it gets up to 160-170
No, the actual copper suction tube that returns to the compressor. It might take some looking to figure that out. The bigger copper tubes are suction. One should come from the evap going to the TXV, then from the TXV to the compressor. Actually either of those would probably be fine. You need a 'bare end' thermocouple. Use ziptie to bond the bead on the tip to the tube tightly. I also recommend some foam around all of that to keep water off of it. Getting water on the sensor will screw up the reading. But all of this should be done on a hotter day. Since you have blocked the fresh air vent, I recommend just trying it for now. The condensate looks to be a big design problem. I am not yet sure how to fix that. There is hardly any condensate consideration in that design.
If high pressure stays low check pump/compressor and/or expansion valve
Dealer claims they checked the expansion valve on the last surface. They say that the compressor is working properly, don't know how they determined that other than there are no error codes.
In the photos, I don't see any evidence of part # 24 or #20 ... insulating tape
Fan on condensor not cooling enough or stuck heater valve
Only tape that I can see seems to be holding a wire to one of the copper tubes behind the fan. I saw a pic in the service manual that seems to show it there too. No specific pics in or mention of the tape in the manual.
Got a call from the regional manager and he says that he watched the videos. He had the dealer pick up the machine yesterday to look at it again.
Update on machine Just got the machine back today. Dealer had it a month. Still not fixed. I actually feel better about the situation now. They finally admitted that there is an issue with the machine and that they have a machine in their rental fleet with the same issue. They did what they could and brought in an outside technician to work on it but weren't able to fix it. Now its in the hands of the engineers at Bobcat who are aware of the problem and will eventually have a solution at which time my machine will be fixed, I hope. The service manager was let go several weeks ago and I have been treated much better since then. They apologized for the issues and the way it was handled.
You need to demand compensation here! It sounds like they have had your NEW machine longer than you! I guarantee how it work with CAT around here is with an issue like that, they will spot you another machine until issues can be resolved. Don't let them screw you around on that!
Don't know about that. Read the new Cat 150 grader thread. Cat never even offered another machine and it's a half a million dollar piece of iron.
When I said "around here" I mean local to me. However, I could be off base with smaller operations. The previous company I was with had about $50M worth of kiddies. Saw several times if we were having an issue, the dealer should show up with another machine when they picked up. As well, I should probably mention that the head super was NOT a guy you wanted to cross. I think they just wanted to keep him happy. Smiling would be pushing it....lol
It probably depends on the location and the dealer.
It sounds like you need to buy lottery tickets.
I understand the dealer has the machine to work on, but I just wanted to check a few things. Air filters into the evaporator/blower unit: from your post quoted, I would like to check which filter you blocked off? The one that sits in the back of the box is the "outside air" filter that pulls air from the hydraulic tank area, this is the one to block off in summer. It's very hot air coming through there. The filter that sits in the cover of the unit, recirculates air from the cab down by by your feet, this is the one to use in summer. Keep the filter clean as it's a dusty place next to your boots. The other thing is the design and sealing of the unit. The "blower" fan, looks like it's a "sucker"? With the intake filters the other side of the heater / evaporator, the air gets pulled through the filters, through the cores, through the "fan" (sucker), then up through some vents? So the cores need to be sealed around to the plastic casing, with some foam insulation and tape/glue, so that the air coming through the filters can only go through the cores to get sucked through the fan. As the photos look, air will take the easiest route which is to go scooting around the whole core and barely through it at all. If you got the picture already from the other guys help, then apologies for being repetitive, but I got the feeling that you might have blocked the wrong filter and not got the importance of the sealed wall the cores need to be in the middle of that box. Cheers. Hope you get the thing working properly.