My A/C suddenly doesn't work. I got it checked out at a A/C shop, and the only way we could get it to work was to bypass the Relay box and to hook it up to power Directly. He told me the computer pcm wasn't turning it on. When i flip the switch to A/C the air blow's but the compressor doesn't come so it isn't cold unless bypassed. He told me to go to an auto electric place to get it scanned, he thinks there is a bad sensor on it or something. I have perfect pressure and full on Freeon. It's starting to get really hot here in Cali Any Ideas will be greatly Appreciated.

 

Same thing happened to me, I would also like to know what is wrong?

 

Same thing happened to mine. I took it to the "professional" AC shop and they determined the same thing... worked fine when the relay was bypassed but otherwise wouldn't. After charging me and telling me they didn't know what was up, I took the car home and thought "Hmm... let me reset the PCM." I disconnected the battery for a few minutes, connected it back up, and AC worked fine and did for years after that

If resetting the PCM doesn't work for you, there is at least one sensor that inputs to the PCM (coolant temp or level? forget exactly) which will not allow the relay to function. That sensor might be bad?

 

A/C pressure transducer(3 wire) or A/C low pressure switch(2 wire)