B4 A/C blowing warm this season after 3 perfect seasons. Details of gauge readings...

I'm having the same type problem with my 96 Passat. A local AC guru has diagnosed it as a bad expansion valve. Parts on the way, and will confirm whether his diagnosis is correct.

EDIT: Expansion valve improved my pressures, but ulitmately required a new compressor, RCV, and dryer. Operation is now perfect.

If I'm not mistaken, a bad expansion valve will give hi side readings normal to high with lo side high as well. With the hi side low, that points to a stuck RCV (refrigerant control valve) inside the compressor.

jeffK14 is correct. It's the refrigerant control valve. I replaced mine with a nut and bolt and now have ice cold a/c, even too cold.

I had the same symptoms, low side around 50 and high side at 120.

chinaloy said:

jeffK14 is correct. It's the refrigerant control valve. I replaced mine with a nut and bolt and now have ice cold a/c, even too cold.

I had the same symptoms, low side around 50 and high side at 120.

Click to expand...

Hey, chinaloy, can you tell me exactly what size & length bolt you used? I've gotta do mine & I want to have everything needed on hand before I tear into it. Thanks.

Jeff, Check out http://www.aircondition.com/tech/qu...Could-Mean-A-Faulty-Refrigerant-Control-Valve

On the bottom of the page is a link to the pdf article.

Same symptoms here this summer after 5 great years. I'll report back with the diag.

The compressor found on our cars is designed such that as high side pressures climb, less refrigerant is allowed into the compressor. The incomming refrigerant is controled by (surprise) the Refrigerant Control Valve. This negative feedback control means that the compressor never cycles off; it just pumps less and uses less power as it pressurizes the system.

If a bolt is installed in place of the RCV, installing a high pressure cutoff switch will also be necessary. Otherwise, the compressor will freeze the evaporator (Too much liquid refrigerant, condenses water from the air, and it freezes on the evaporator.)

If anyone wants to try a used RCV, I have 2. One is out of a members used compressor, another is out of my own. Both compressors required replacement, so the valves are probably good. If you want one, please send me a PM.

I would try replacing the RCV in 2TDIguy's car, as his compressory clearly functions. (50/120) I would also drain the compressor of oil and refill. This will remove some wear particles from an old compressor and it will only take a couple minutes once it's off the car.

Also if you have the time, take some pictures of the RCV replacement. It would be good to have a write up. I failed to do so after I forgot to take my camera to my shop.

FYI, we put a new comp. and the issue is clear. Back to 34 degree B4 A/C.