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Kevin
Kevin, Technician
Category: Agriculture and Farm Equipment
Satisfied Customers: 731
Experience:  Over ten years of expirence in Ag Electronics and Hydraulics
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I have been working on a J.D 4050. I have been doing A/C

Customer Question

I have been working on a J.D 4050. I have been doing A/C system repairs. The evaporator was completely clogged. I recovered the existing R134A. I replaced the evaporator, high pressure switch, low pressure switch, TXV, receiver/dryer and thermostatic switch. I installed new cab filters and replaced all the seals for the pressurizer chamber. Vacuumed the system for 45 minutes and charged with 3.25 Lbs of R134A using a Robinair unit. Thermostatic switch is engaging the A/C clutch like it should. Low/High pressure indicator lights come on for about 5 seconds then go off like they should. Air temp at vents is not cool at all. Also I see nothing in the sight glass of the receiver/dryer. I have been charging A/C systems for years, but this tractor only has a low side port. Do you have any information on this system, and any ideas about why I am not getting cold air?
Submitted: 5 months ago.
Category: Agriculture and Farm Equipment
Expert:  John Oliver replied 5 months ago.

good morning my name is ***** ***** i can help you. what are your pressure reading on the high and low side and what is the ambient air temp?

Customer: replied 5 months ago.
Did you read the whole Question? There is no high side port! Ambient air temp is about 95* and the pressure reading on the gauge of the Robinair unit was about 100 psi after charging with the amount of refrigerant required.
Expert:  John Oliver replied 5 months ago.

good luck

Expert:  Kevin replied 5 months ago.

Hello, my name is ***** ***** I believe I can help you with your question.

Ok so it so I want to first let you know that Deere offers an update kit that eliminates the old pressure lights in the overhead. The kit consists of a wiring harness and I believe one hose that puts the pressure switch in the circuit with the compressor much like a modern vehicle or tractor. I believe that the kit will provide you with the high pressure fitting. That being said the lack of the kit is Not what is causing your tractor to fail to cool properly.

I see you have done a very through job on the Evaporator end and have the proper approximate charge in the system. My first thoughts are that we might not be doing a good job cooling the condenser. If you haven't already take a few minutes to make sure the side screens, evaporator, and radiator are as clean as possible. Next check the viscous fan clutch to make sure it is locking up properly. The cooling systems on 4050 tractors are actually far more then the engine requires so they often operate for years with a faulty fan clutch. The next item that comes to mind is the expansion valve. Check your low side pressure with the tractor running at about 1,500 rpm, you should have between 15 and 22 psi. If the low side pressure is in the single digits or way over 22 psi then I would guess that the expansion valve has stuck. I have personally stuck brand new expansion valves just after reassembly due to rust in the high pressure lines going up the back corner of the cab.

Ok lastly I want to address the receiver dryer sight glass. It has been my practice that on R134a systems to completely ignore the sight glass as it is often way to misleading. I generally shoot for between 3.25 and 3.5 lbs of R134a on 50 series cab tractors so you a right in the ballpark.

Let me know what you are seeing.

Thanks,

Kevin

Expert:  Kevin replied 5 months ago.

Hello,

I just wanted to check in to see if you had gotten your cab cooled down yet. Please feel free to let me know if I can be of any further assistance.

Thanks,

Kevin

Customer: replied 5 months ago.
Have not gotten it to cool yet, but I have haven't been able to work on it for the last couple of days. The customer has been using it in the field. The clutch is engaging. I took the front cover off of the pump to make sure of this. when I run the engine the psi is around 100. Condenser & radiator are clean and airflow across the condenser is good. The problems that I think I have is that as soon as I start charging the system, the pressure immediately jumps above the low pressure target. Possibly a stuck expansion valve? It is brand new from AP Air Inc.
Expert:  Kevin replied 5 months ago.

The expansion valve is the most likely suspect. It wouldn't be the first time I've seen a expansion valve stick right out of the box. I've often wondered if small scale or rust inside old lines doesn't break loose causing the problem. Its also possible that the valve was simply defective. I hate to say it but I would suggest replacing the expansion valve again. Keep me posted.

Thanks,

Kevin