Hello . I'm working on the air condition on a 4040 John Deere tractor and I have been having this problem when I charge with the R134 refrigerant. the gauge on the low or suction side is about 22 the hi side is about 320. everything is new .hoses ,evaporator , condenser , Expansion Valve and the compressor . I have put vacuum the system many times look for any blockage of the system and everything is in order. the ac is cooling pretty good but the pressure on the hi side at 320 is to hi . the factory compressor if you familiar with this model tractor you know that looks almost identical at the GM Chevy 1967 to 1980s The compressor that I purchase it belong to a Chevy Camaro 1968 from auto zone it is the four season brand model #57089. paid $239.00 now the john Deere compressor can cost for $350.00 to $700.00. I'm starting to wander is I make a mistake on using this compressor maybe they are exact the same on the outside but not on the inside. Can someone help and explain to me if I make that mistake . Thank you
Maybe the receiver/dryer is stopped up?
Consider the receiver/dryer your filter. You didn't state that it had been replaced. Your compressor isn't the issue.
Your issue is airflow across the condenser. Pulling a vacuum on an A/C system does not suck anything out. It lowers the pressure so moisture will boil out at room temperature. Clean the debris out of the condenser and radiator. You can prove my diagnosis by adding some additional cooling to the condenser, use a garden hose and spray it down while running. You high side pressure will drop.
Is there any possibility the system is over charged ? Or even too much oil in it ?
the receiver/dryer is also new. I did open the system again and blow compressor air to the receiver/dryer and it was not clog . Another thing is that the compressor gets very hot . The system is not over charge and also the oil.
How are you determining how much refrigerant is being put into the system? Have you tried to bleed any off? Did you add compressor oil?
Good point about the oil. Did you drain and measure the old compressor's oil? The new compressor should be drained and refilled with now oil to match what you removed from the old compressor. New compressors typically come with way more oil than needed. Did you try cleaning the condenser and adding some extra cooling? Easiest way to know if you have a blockage where it doesn't belong is to note where it gets cold. It should get cold after the expansion valve. 22 PSI is 26 deg F. That is too low but not by much. Your high side is high but not crazy high. What is the ambient temp? The compressor is hot because 320 psi is over 150 deg F. You can find a pressure/temp chart for R134A by using Google. I am assuming you have an expansion valve system with a fixed displacement compressor. Can you confirm?
sorry for late reply .I was are work. thank you for all the reply .I have the expansion valve system .The new compressor comes with 3 oz of oil and the system is a 11 oz . I add 8 oz of oil . when I was charging the system it will take so long to add the refrigerant only because it will take only a little at a time I have done many cars and trucks ac and it will not take so long.I did stop when the hi pressure got to 325 because I was afraid that one of the hose will explode .The compressor for the John Deere it looks the same on the outside to the 1968 Camaro. What I want to know why is such a difference in price the John Deere will run around $500 to $700 and the Camaro will be $220. the first picture is the John Deere and the second is the 1968 camaro.
The compressor is the same. John Deere just marks it up more. I had an old Jaguar and compressor from Jag was over $1000. A brand new GM one, not a knock off, was $200. It sounds like you are not weighing the charge you are putting in. Just kind of guesstimating it. If the system holds 11 oz total of oil you should not add 11 oz when charging. You need to only add what was lost during evacuation and repairs. That being said over oil is not your issue. Have you replaced the expansion valve. It should try and keep the evaporator above 32 deg F. In your case your low side is too low.
Everything is new expansion valve is new, the compressor accumulator ,condenser, evaporator , hoses. after I install everything I vacuum the system to -30
I can put more refrigerant but the hi side is going to be going up
Do think that the expansion valve even if is new maybe defected .Can buy another one and try that . Right now a evacuate the system again for the 4 time .At this point I will try anything. It is very frustrating that everything is new and I can get it to work right
Was a retrofit kit installed on the tractor ? If there was then the the expansion valve should be the correct one. If the kit wasn't installed then there is a possibility the expansion valve is part of the problem.
If the system is vacced right you should hear the freon rush into the system the moment you crack open the low side valve. so I now have a few more questions...... 1. When you vac the system, are you opening both the high and low valves? 2. Are you vaccing for at least 1 hour? 3. When you finish the vac operation, are you closing the high and low valves? The high will no longer be open throughout the rest of the charge process. 4. When you do your initial charge with the engine dead, will the compressor come on once you start the engine? You should have enough freon to open the low switch. It almost sounds to me like you are not getting the system vacced down as it needs to be. You really should have an air temp gauge in the vent to help assist the process. Ideal vent temp is 35-45 degrees.
How long did you leave it on a vacuum? You said you blew it out with compressed air which on top of being newly assembled can introduce a lot of moisture. I would clean out the radiator and condenser and leave it on a vacuum over night then try it again. Does the engine have a fan clutch or direct drive fan? It is also possible you got a bad compressor if it was a reman. I personally loath those old GM compressors. I would have adapted a Sanyo type to it if the mount wasn't too big of a deterrent.
When I vac the system I do it for an hour before I turn the vac machine off by them the gauge is writing -30. I closet both side Low and Hi, them I wait about 30 min and make sure that the gauge have not change from -30 . after I remove the vac machine I will now connect the R134 cylinder and start the charging process . The only thing different that I done if that I start the tractor and turn the AC on and them I start charging to the low side keeping the hi side close gauge on so I can read the pressure on the hi side . The engine don't have a fan clutch
Just order a new compressor. This time I order a John Deere AC compressor . I will get it on Thursday so I will be posting this weekend how it does work . Don't know what else to do, it is very frustrating when everything is new and can't get it to work right. Thanks every for the help
John Deere AC compressor
That is not the same compressor as you posted earlier. This newest picture looks like a Sanyo. That being said I am faiirly confident a new compressor will not fix your concern. This compressor works. You are building pressure. From what I am reading you are not using a scale to charge your system. You need to measure the proper charge. BTW. Pulling a vacuum for hours or days does not do anything magical. The vacuum boils the water out of the system. Nothing more. It does not suck dirt out or make passages clean. After reading your posts for clues and knowing your system is basically new and you have verified the parts are good. I would say your expansion valve is the issue. Your low side pressure is too low. Is the expansion valve an H block design or does it have a bulb you shove in the evaporator? Remove the expansion valve and look for debris. If the hoses are old they could be coming apart inside and little bits block the orifice in the expansion valve. There are slight difference with an expansion valve made for R12 vs. R134a but honestly your issue would actually be a slightly warmer off coil temp if you used an R12 exp. valve on an R134a system. Based on your pressures your off coil temp should be 25 deg F. If you measure higher than that are you measuring right at the evaporator or at the outlets?
The OPs gauge readings are consistent with an overcharge or lack of air flow. The charge conversion factor is approximately 70% to 80%. A system designed for 32 ounces of R12 should only be charged with about 24 ounces of R134a. I didn't say anything about a vacuum sucking out dirt or cleaning. The ability and effectiveness of leaving a system on a vacuum depends on the amount of moisture in the system. 15 minutes to an hour may be fine on a system that has been properly flushed and purged with dry nitrogen. Leaving a system open to atmosphere and making it worse by blowing compressed air through it you may never get all the moisture out. Leaving it on a vacuum for an extended time might have a chance. Any time you change from R12 to R134a you need to change the expansion valve or orifice to one that is made for the different refrigerant. The seals, hoses, and compressor tolerances in older systems may not be up to the task. I have seen older compressors that you could not stop the front seal from leaking using R134a. The molecules of R134a are smaller than R12, so it may leak out of the flare fittings and hoses which were in use by previous R12 systems. A restricted or undersized expansion valve or orifice would result in a low, low side reading.
Those systems are made for r12 that being said I've tried to make them work on 134a it always does what you got going on my best advice is to flush the system and change the expansion valve drier and convert the compressor to a sundan 4334 compressor get you low side between 10 and 20 psi and the high side at 140 to 160 ish and you'll beable to hang meat in the cab on a 100 degree day
this is the expansion valve for R134 . All the hoses are new . I'm measuring at charging port on the compressor
An overcharge condition will have higher than normal readings on both the high side and low side. Actually the conversion factor is 90% minus .25 lb. I did not mean to insult you. Urban legend/common mistake is that the vacuum is to suck out stuff. Sorry if I hit a nerve. Was not my intention. Since that is an expansion valve with a separate build your low side reading could be a result the capillary bulb not making good contact with the evaporator. Make sure it is getting a good contact so it can adjust the orifice properly. I have converted hundreds of A/C from R12 to R134a in my career. Yes the hoses, o-rings, seals, orifice/expansion valve and oil are all different. The expansion valve is calibrated for the pressure/temp relationship of the specific gas. R12 and R134a are so close that if you use an R12 expansion valve on an R134a system you will only see evap temps a little warmer by a few degrees. One last thing about conversions. R134a is less efficient than r12 so you will lose some cooling capacity. In cars of the r12 era they were so oversized it didn't matter. In a piece of equipment with all the glass this may not be the case.