Lately my AC has been acting odd. It will mainly have vent air temps around 20C (with the system set to 20) but sometimes it will drop toward 8, and then come back to 20-25. If the car has been sitting in the sun it doesn't go to max cold, but sits around 20C vent temp.

I put my gauge set on the system and when it was showing 20 vent temp with the system set to "LO" the pressures were 90 psi low side, 140 psi high side. Obviously the suction pressure is way too high.

I was reading in JTIS and saw this: "The compressor has a variable capacity via an internal valve, which can by-pass volume through the compressor when required. Compressor output varies from 100% to 30% depending on refrigerant demand, the variation being governed by the internal valve within the compressor housing."

Could it be that the compressor is internally bypassing the refrigerant? I assume it's time for a new compressor then?

 

There is a PDF attached to my response. The valve in question is on the rear of the compressor and you might have to remove the oil filter to get to it. The refrigerant must be removed.

After that the diamond shaped cover with two bolts has to be removed and the spring and cup taken out. Next put the cup in FIRST and then the spring Second. Bolt the cover back on. If there is a leak you may need the O-ring but usually you can get away without it.

The newer style Compressors do not have this valve, if your compressor doesn't have a cover with two bolts it is probably a new style and the problem may be something else.

 

Thanks very much! When my hoist is free I'll have a look at that valve.

 

Am I correct in believing that the valve & spring do not need to be replaced? Just swap positions and refill...? Clever. My high side is low, low side high, system will not accept more than 12oz of R134a after I changed the orifice tube.

I am hoping its not a blown compressor, its not an easy job in comparison.

 

I followed the TSB and changed the positions of the valve and spring. My vent temperatures went from about 3-5 degrees under ambient to a solid 3 degrees when moving. Nice cold AC, so thanks for posting the TSB!

 

my new OEM compressor has this valve, apparently.

I just bought it. I wonder if I should change the possition of the spring before having installed or if it already comes that way. Don't want to start opening up a new compressor unnecessarily

 

Idk if the schematic here will be helpful or not =

https://redirect.viglink.com/?format...fficiently.pdf

 

I'd change it the new ones don't have the valve.

 

 

^ that being said, there are numerous posts by owners who did not switch the valve/spring which in essence disables the function of the valve and replaced the compressor (w/spring-valve) & had no problems for the rest of their time owning or still own their X.

 

If you need to change it in the future you need to de-pressurise the system change the valve then vacuum and re-charge, I'd just switch it. YMMV.