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Discussion Starter · #1 ·
Can't seem to fix the a/c on new to me 1640. Had a leaking high pressure hose, replaced that, evacuated system, no leaks, started charging system and all at once the compressor clutch will kick out and low pressure light will come on in cab. Also the fan motor will quit and try to start then quit, etc.. Could it be the air conditioner relay in the cab? I have checked the ground and it seems to be ok. May need to say that we have 3 cans of 134 already in the system. If you shut the combine off and let it set for a while everything works until the low pressure light, clutch kicks out, and fan starts starting and stopping.
 

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Discussion Starter · #2 ·
I put a new a/c relay in this a.m. When the system starts to cool, the relay will kick out and the green wire that comes from the relay to the fan switch will loose power. Could the compressor clutch be drawing too many amps?
 

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Have you put some guages on the a/c system they should tell you the problem . I remember on our 1480 we had a problem like that and it was the reciever drier it had started to break down inside and the crap was plugging the expansion valve . Would be really suspicious of that concidering that you changed over to 134 . I think that there is different dessicant in the 134 systems . And did you change the oil in the system when going to 134 as the old mineral oil in the r-12 system is not compatible with 134 you need an ester type oil for that refrigerant and it's a pain in the a-- to chang as the whole system should be taken appart and solvent ( i use brake clean ) to wash out the old oil . I've found the easy way is to use these non cfc butane based refrigerants such as duracool or redtech which easily replaces either r-12 or 134A . you don't have to change any oil then and they are about 10% more efficient IE better cooling . The thing to look for with the guages is a high initial high side pressure then it droppes off when the cooling stops and the low pressure will be at 0 or a vacum . Or the high pressure really gets high 200psi+ . What is happening is the compressor has pumped all the freon to the high side and the plugged expansion valve or reciever won't let any through and the pumping just quits and pressures drop because there isn't any heat exchange through the expansion core ( the one in the cab ) the core at the rad is probably full of nice cool liquid freon that isn't going anywhere to pick up heat so the pressure drops but if the pressure is going sky high that is dangerous as the condensor and piping is full of liquid and the compressor is still finding some freon vapours and is truing to pump them to the high side . so don't go and put more in or you could blow the compressor or something else .
Marshall
 

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I had a 5088 that had a similar problem. Spent alot of money on it before replacing the temp control switch. That fixed it. Not sure if your controls are the same as a 5088 A.C.
I am on here looking for tips on replacing a rotor belt. Any experiance with that?
 

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Discussion Starter · #5 ·
Finally got it fixed. The a/c on this combine had a multitude of problems. After the above repairs, I found the compressor was leaking out the front. Replaced that and then determined the expansion valve was bad. While replacing that, I also replaced the drier. Then I replaced the temp switch and the low limit switch. Probably didn't need to replace the low limit switch. Ran the combine yesterday and the a/c works fine. Sorry, don't know how the replace the rotor belt yet.
 
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