Automotive Air Conditioning Information Forum (Archives)

Truckdriver09 on Tue January 07, 2014 12:41 PM

Year: 1997
Make: Volkswagen
Model: Passat TDI
Engine Size: 1.9L
Refrigerant Type: r134a
Ambient Temp: 80
Pressure Low: 20
Pressure High: 20
Country of Origin: United States

I have a 1997 volkswagen passat TDI. I tried using the a/c yesterday and the air would only blow cold for a few minutes and then goes warm. I tried again today and the same result. I threw on a set of gauges and I'm getting 20 psi for the low side and the high side and the compressor clutch is spinning, can you tell me what this means?

TRB on Tue January 07, 2014 8:03 PM

These compressors are known to have control valve failures. If the system is correctly charged? I would be looking in that direction.

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Truckdriver09 on Wed January 08, 2014 11:56 AM

I'm not sure if it is properly charged, I thought maybe it was just low on charge, so I added a little bit and it didn't change the pressures, so I stopped because I was afraid of possibly overcharging. Is there a way to test this valve?

TRB on Wed January 08, 2014 12:46 PM

Nope it is internal and you would have to tear the compressor apart to replace it.

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Truckdriver09 on Thu January 09, 2014 2:23 PM

Is it worth it to tear apart the compressor and replace the valve, or just replace the compressor itself?

Is it safe to assume that the cause of the low pressures are coming from the compressor? I'm not sure if the system has the proper charge, but the clutch never once stops spinning while I have the a/c on, so even if the system is undercharged, shouldn't at least the high side pressure be higher than 20 psi? Or is that incorrect?

TRB on Thu January 09, 2014 9:38 PM

It not supposed to disengage with this type of compressor. Reclaim the refrigerant, evacuate and recharge to OEM specs./ If pressures are the same you know there is a good chance it is the control valve.

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