Has anyone checked to see what the temperature is at the vents on thier skid? I had to do a good bit of A/C work on my Case and the best I can get is around 50*F on a hot day. I never could get the pressures to read what I thought they should but they are close. It seems like my system has a problem with air flow across the condenser. Everything is clean I think it is just a matter of the way the air is drawn in. I had the windows tinted and I can live with the way it is now but would like to know what temps others are seeing.
the magic number is a 30*F difference between inlet and outside air temp. most that i see are 46-50*F outlet temps :drinkup
Depends on the outside air. 50* isnt too bad for hot summer , sounds like it can't cool the cab though? Need more air flow? Does it have a fresh and recirculation filter? Cap the fresh one, no need for it until winter if at all. What were the pressures doing? If airflow across the condenser is an issue the high side should climb and you will feel the air getting warmer. If condenser is perfectly clean and still can't perform well, maybe you can relocate it with its own fan. What model machine is it?
The machine is a 2007 Case 450. I bought it last year and the air has always worked but has had a very small leak. I have had to add freon 2 times over the last year. A few weeks ago the air quit so I got a gauge set and the high side was hitting 400 psi and cutting the compressor off. I figured it had a restriction so I replaced the dryer and txv valve. I also had to replace the compressor because the high side fitting broke when I tried to remove the hose. I got everything back together and the pressures are 210 on the high side and 20-25 on low side. This is with 18oz of R134a on a 90* day. I tried adding more but it made things worse. The A/C only has an ON mode. There are two vents that open and close for recerculate but not really sure they do much good. I went though the system top to bottom and removed and cleaned the evporator and condenser while I was waiting on parts. 50* on a 90* day may be best I can get. The air is being sucked down across the condenser then blown though the radiator and oil coolers. The higher the RPM the better it cools. I think it would be better if the condenser was in front of the radiator. The A/C on the series 1 machines really look like an after thought.
Around 50F is what I look for on my tractor AC systems. 20-30 psi low side and 250 - 300 high side at 3/4 rpm and everything clean with OUR usual summer temps 95-100F. I keep an old bulk drum handy to play with pressures. 25-50 psi change on the high side can make a lot of difference in outlet temps. Spray your condenser with water while it is running and see what happens.
I thought about spraying water on the condenser but was in the shop. I'm not an A/C tech so just went by the chart first time I charged it and got pressures to 300 high and 25 low. This only got me to 60* so I started over. One thing I did figure out was that if the cab and engine cover are up the sytem won't charge correctly because of the way it draws air across the condenser. Problem is the cab has to be lifted to hook up low side and engine cover can only be closed 3/4 while charging. I ended up checking the pressures on my feed truck and just getting them close to that. I may check my tractor temps and see what they are on a hot day. Funny you say you use an old barrel. I ended up using an old gas can.
A 30º drop is not bad, you may still be a little low on freon. Try and shoot for around 25-30 & 250. The high side pressure will start to climb quickly when you are full. Basically you want just enough freon that the high side of the system will be full of liquid, old cars used to have sight glasses so you could see when it went clear with no more bubbles. Once it's full the high side pressure will really start to climb and you've gone to far.
Was the condenser dirty when you cleaned it out? What was the low side at when you saw 400 on the high side? The reason I ask is that it's possible the condenser was just dirty and caused the high side to climb and kick out compressor. If the TXV is stuck closed or there's a high side restriction the low side will read very low or vacuum sometimes. When you replaced the parts did you evacuate the system? Air and moisture contamination will reduce the cooling as well. I'm no expert, but I like to add freon based on a few things. Knowing the systems capacity can be helpful. I watch the gauges to get it close then add 4oz at a time until the vent temp doesn't drop anymore, then you are at the max cooling you will get. They don't seem to teach that last part, but a lot of people seem to have good success. If there's a sight glass it can be helpful as well.
When the high was going up and low side going down before I replaced anything. Probably 400 high 10 low side. The condenser was dirtier than I thought but not bad enough to cause it to kick off on high pressure. The A/C calls for 18oz of freon and 8 oz of oil. I would guess I have around 20 oz of freon in it now. The thing I can't figure out is that the low side never reaches 30 psi even when the high side was at 300 low side stayed at 20-25. I did evacuate the system for 45 minutes and then let it hold vacuum for about an hour. I'm no expert on this stuff. Think I'm going to run it for a couple days next week and then check the pressures again. I did add some dye to the oil so I can check for leaks also.
Don't add oil unless you are replacing components that hold oil. Too much oil will reduce your cooling and increase the high side pressures.
I replaced the compressor and it came with the required 8oz of PGA oil. I only added about 1.5 oz of the dye. I had blown out all the lines, evaporator, and condenser so I don't think I have to much oil.
You should be fine, sorry I missed the part about replacing the compressor. Remember reading it but it didn't register.
I think it will be good. I go a little overboard with repairs sometimes. Think I like working on equipment more than running it. I just like things to work correctly. Especially when I'm able to work in the shop. Out in the field can be a different story.
I had a lot of problems with the a/c on my deere and ended up putting a red dot pressuring system on an never looked back
Did you put the roof mount system on? I've been looking at cab pressurizers but haven't seen an entire system yet.
By bulk drum, I meant an empty R134 30 pound drum. I can dump the high side into it and then feed it back into the low side and see what pressure cools the best without losing refrigerant. Cool it somehow (radiator intake airflow, bucket of water, etc.) and it can nearly empty a system. My poorboy evac system.
I made a bracket and bolted it behind the rops bored a 3inch hole through the top of the a/c housing throw away the filter to make room for the new brackets. And wired it to come on with the fan i can get some pics.
hmearth I would like to see a few pics if it's not too much trouble.
Js300 you can it is set up so no vision is lost and it is not to high to get damaged by trees
hmearth if I am looking at that right it is a pressurizer to go along with the factory A/C and not a complete roof mount A/C. If so thats what I have been looking for. I have allot of trouble with dust and hot air getting sucked in the cab and think a pressurizer would be the ticket. Red Dots website isn't the best and it's hard to get prices on thier stuff. Mind me asking what it cost? I'm using my phone and it's a little hard to see the pics but will look at them again tomorrow. Thanks for the pics
The red dot unit will boost air and pressurize your cab the part number is red dot 78R5110. you will need to remove existing filter in your cab block all factory inlet holes to a/c bore a 3'' hole in the top of a/c unit be careful at this stage make a bracket to suit hole and take a 3'' pipe for inlet wire new fan to come on with existing unit. Start to finish your looking at a $1000 with extra hardware you'll need
I'm not to sure how this unit will mount on a case but when mounting you need to make sure vertical lift if you have one bonnet and engine intake does not foul with the unit
Thanks for the info. I'm going to look at the mounting location next chance I get and see if it will work out. More air through the vents and pressurization is just what I need. Thanks again