Q&A

 Journeyman

There are two sides to an A/C system, the control side and the mechanical side. The control side would be the switches, relays and electrical power that turns the A/C on, and the mechanical would be the actual A/C components itself. You will have to determine what is not working when the A/C blows warm and then diagnose what ever side is failing. Check to see if the compressor is on when it blows warm air. If it's still on then it's on the mechanical side, if not then look to the control side.

This may sound like a stupid answer but it worked for me. My engine coolant was quite low and when the engine started to reach a high temp level (engine was not near overheating) the computer shut down all non essential items and as such a/c is not required. After 2 trips to the dealership and they replaced two sensors that they said were faulty causing my a/c to cut out, I looked at my repair manual and the first thing it said to check was the coolant level. It was down so I topped it up and never had the problem again. To this day I have never trusted dealers again.....Chris