My car is a '04 civic with ~140,000km. Last year my a/c stopped blowing cold air. Sometimes it would cut in and blow cold air then gradually never worked at all. My compressor doesn't cut in at all. I brought it to a garage the mechanic figured it was low and needed to be recharged. He checked it and it was down a bit on pressure, so he refilled it and still don't work. He said that the computer was reading that there is no pressure in the system. Also he tested the compressor and it was fine. Anyone know what could be causing this?? Thanks.

 

Does the condenser fan also fail to run?

 

Find a better mechanic. When the system works sometimes that means it has enough refrigerant-- there aren't any gremlins under the hood who take your R-134a away and put it back on their whim. Once it's leaked out it's gone for good.

The two big reasons for the compressor working intermittently are the clutch gap being too wide, and on your model, the compressor thermal switch. Those switches were sort of a lemon part those years.

The good thing here is it now never works at all, as intermittent problems are a real bear to troubleshoot. This needs to be tracked down by some electrical tests, and if your mechanic is one of those who recoil in horror at the mention of an "electrical problem"-- find a better mechanic or do it yourself.

 

Is there a way I can test the compressor thermal switch?

 

Does the condenser fan fail to run? If the fan does not run, then there are other possible explanations.