A/C compressor runs but no cool air
08-09-2002, 05:10 PM
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A/C compressor runs but no cool air
I bought my 928 three months ago. The PO said there is no refrigerant in the A/C system so the compressor won't run. I had the A/C system filled and after that it worked okay (well, it didn't blow extremely cold air but quite cool anyway).
After a month or so, a hissing noise started coming out of the center vent whenever the engine was running. The A/C still worked fine. However, one day it just wouldn't work anymore. The hissing noise is still there. I checked that the compressor runs (the center part of the pulley spins) when I turn on the A/C, but there is no difference in the temperature of the incoming air (temperature control at lowest setting).
I thought the hissing noise could be a vacuum leak. I verified that at least the recirculation flap (passenger side, under the glove box) operates, so at least there is some vacuum in the system. Also the temperature control works, if I turn it to hot I get hot air normally.
Looking through the glass inspection window at the front of the car I can see a sort of vibration in there when the A/C is on. But no bubbles or anything.
Any clues what could be wrong?
Best regards,
Niklas Kampe
Porsche 928 S4 '87
After a month or so, a hissing noise started coming out of the center vent whenever the engine was running. The A/C still worked fine. However, one day it just wouldn't work anymore. The hissing noise is still there. I checked that the compressor runs (the center part of the pulley spins) when I turn on the A/C, but there is no difference in the temperature of the incoming air (temperature control at lowest setting).
I thought the hissing noise could be a vacuum leak. I verified that at least the recirculation flap (passenger side, under the glove box) operates, so at least there is some vacuum in the system. Also the temperature control works, if I turn it to hot I get hot air normally.
Looking through the glass inspection window at the front of the car I can see a sort of vibration in there when the A/C is on. But no bubbles or anything.
Any clues what could be wrong?
Best regards,
Niklas Kampe
Porsche 928 S4 '87
08-09-2002, 06:02 PM
#2
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Niklas-
If the compressor only spins when you push the AC button (as it should), then it is possible there is enough refrigerant to allow the compressor to run but not enough to cool. Maybe your refrigerant is slowly leaking out. At some point in the future, if you press the AC button and the compressor does not spin, then there is probably a leak. The hissing noise is probably not a leak - just the sound the expansion valve. You will need a set of guages and a thermometer to troubleshoot this. Does your system use R-12 or R-134a refrigerant? How's the weather there?
If the compressor only spins when you push the AC button (as it should), then it is possible there is enough refrigerant to allow the compressor to run but not enough to cool. Maybe your refrigerant is slowly leaking out. At some point in the future, if you press the AC button and the compressor does not spin, then there is probably a leak. The hissing noise is probably not a leak - just the sound the expansion valve. You will need a set of guages and a thermometer to troubleshoot this. Does your system use R-12 or R-134a refrigerant? How's the weather there?
08-10-2002, 08:32 AM
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I agree with Steve.
My AC stopped providing cool air even though the compressor was working. Had it filled on Thursday and now it's cool again.
Probably a slow leak somewhere.
My AC stopped providing cool air even though the compressor was working. Had it filled on Thursday and now it's cool again.
Probably a slow leak somewhere.
08-10-2002, 06:16 PM
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Thanks for the tips. I will have the system checked by an A/C service specialist to see if it's low on refrigerant. It did not show any gradual degrading in cooling efficiency, it just stopped blowing cool air one day. I thought it would gradually start working less and less efficiently if there was a leak?
The system was last filled with an R-12 replacement called R-413A (legal in Europe). Today it was 26 degs C (79 degs F), pretty warm for Finland, so it would be nice to have the A/C working...
The system was last filled with an R-12 replacement called R-413A (legal in Europe). Today it was 26 degs C (79 degs F), pretty warm for Finland, so it would be nice to have the A/C working...
