6070 air conditioning problem

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   tractor has updated pump 134a conversion, worked fine earlier this spring after adding a can. now that it's hay time it won't kick on. i have power to and through the high pres switch and that's as far as it goes. i took the wire from the high switch and connected it to the clutch bypassing low switch and it kicked on, added a can of 134 low side, took it no problem. pressures are 120 high side and negative 10 low side???? no cooling happening. i have never run into this before. any ideas??

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rieg Members Profile Send Private Message Find Members Posts Add to Buddy List Silver Level Joined: 17 Sep 2009 Location: swoh Points: 354	Post Options Post Reply Quote rieg Report Post Thanks(0) Quote Reply Topic: 6070 air conditioning problem Posted: 25 Jun 2019 at 10:31am
	tractor has updated pump 134a conversion, worked fine earlier this spring after adding a can. now that it's hay time it won't kick on. i have power to and through the high pres switch and that's as far as it goes. i took the wire from the high switch and connected it to the clutch bypassing low switch and it kicked on, added a can of 134 low side, took it no problem. pressures are 120 high side and negative 10 low side???? no cooling happening. i have never run into this before. any ideas??
	rieg

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DrAllis Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Points: 19473	Post Options Post Reply Quote DrAllis Report Post Thanks(0) Quote Reply Posted: 25 Jun 2019 at 11:32am
	Add another can, you are still LOW.

rieg Members Profile Send Private Message Find Members Posts Add to Buddy List Silver Level Joined: 17 Sep 2009 Location: swoh Points: 354	Post Options Post Reply Quote rieg Report Post Thanks(0) Quote Reply Posted: 25 Jun 2019 at 3:07pm
	Thanks Doc but no help added another no help so i added another same thing pulls down to minus 10 low side and about 110 high side, no cooling, also no bubbles in site glass. To full?? Just pumping fluid?? That was 3 cans total plus what was already in it. Still have r12 in everything else, not that up on 134a. Maybe expansion valve and to much fluid??
	rieg

LB0442 Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 27 Dec 2014 Location: Boise ID Points: 767	Post Options Post Reply Quote LB0442 Report Post Thanks(0) Quote Reply Posted: 25 Jun 2019 at 5:20pm
	After a couple of cans you should see at least 10 to 20 lbs on the low side. If it has a vacuum on it then there is a blockage before it. I would look at the expansion valve not opening up allowing gas into the evaporator. The only problem with that is your high side is not that high for a complete blockage. Check the dryer for a cold line after it, sometimes they will plug up and act like a restriction, Freon will flash off there and have low pressure before it gets to the evaporator. Does also sound like it may have npn condensable (air) in the system, thatwill do some really weird things with pressures.

joelsplace Members Profile Send Private Message Find Members Posts Add to Buddy List Silver Level Joined: 07 May 2019 Location: Northlake TX Points: 74	Post Options Post Reply Quote joelsplace Report Post Thanks(0) Quote Reply Posted: 25 Jun 2019 at 5:22pm
	If you had too much 134 the high side would be way too high. From your readings you are way low and that is why it wouldn't kick on. Probably needs 20psi or more on the low side to kick on. -10 and you are starving the compressor for oil. Oil travels in the 134. I would say it mostly all leaked out. Get out the soapy water and spray down everything to find your leak. A bad expansion valve could cause the low low side pressure but it would also have a corresponding very high high side pressure.
	1975 7040 w/Power Director

DrAllis Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Points: 19473	Post Options Post Reply Quote DrAllis Report Post Thanks(0) Quote Reply Posted: 25 Jun 2019 at 5:36pm
	I thinking expansion valve is stuck closed after adding that much juice.

rieg Members Profile Send Private Message Find Members Posts Add to Buddy List Silver Level Joined: 17 Sep 2009 Location: swoh Points: 354	Post Options Post Reply Quote rieg Report Post Thanks(0) Quote Reply Posted: 25 Jun 2019 at 10:06pm
	I have been working on these systems for over 40 years and never ran into crazy pressures like these, pulling a vacuum on the low side while adding gas to it makes no sense. Yes it was taking the gas with no problem, the can was completely covered in frost. With engine off the high side would not take any liquid at any time during this process?? any clues?? not even with the first can??
	rieg

Brian Jasper co. Ia Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 11 Sep 2009 Location: Prairie City Ia Points: 10508	Post Options Post Reply Quote Brian Jasper co. Ia Report Post Thanks(0) Quote Reply Posted: 25 Jun 2019 at 10:29pm
	You have a clogged or stuck closed thermal expansion valve. When that happens, all of the refrigerant ends up in the condenser and doesn't make it to the evaporator. If no refrigerant gets to the evaporator, no refrigerant gets to the compressor. With no refrigerant to pump, the high side stays low because of the air flow through it. I'll bet the dessicant bag opened and the material is stuck in the TXV.
	"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford