Ok.
The AC does turn on if I manually ground the relay thats in the engine bay fuse box. Without manually grounding the relay the AC does not turn on. The compressor does not spin.

1.) I have changed the low pressure AC sensor that sits on the AC line next to the passenger side shock mount. This did not work.
2.) I know the compressor is getting good power because it works as long as it's ground.
3.) I know the AC signal gets sent to the computer to Turn on my AC. When I turn the **** to AC the snap on computer reads that the AC has requested I turn on my AC.


Could it be the relay itself that is bad? And Not grounding properly?
Could it be my OBDI that is bad?


Looking for any ideas or places to look? Thanks.

 

Did you recharge the system? I think thee system needs something like 31 psi to even turn on.

 

With no high pressure low pressure gauges you cant do ac, need some readings they tell you everything you need to know... High pressure on gm should be not be higher than 300 or you cook the compressor, low no lower than 50... I would do the suck and pull test to the compressor see if the seals are broken if it works. You can replace dryer and Orphis(spelling) tube, put UV die and look for leak..... If compressor is dead it shot all types of bad stuff into your system and you must replace all the above and flush system complete... IS the air hot, did go hot, or does it just not turn on? It will NOT work if pressures are off....

 

The AC compressor is actually the 2nd one I've had in the car. I replaced the compressor with this used one on an engine rebuild. My 1st compressor stopped working and I thought it might be the unit itself. So i dont think its bad..

The AC system was recently fully charged and dye was put in with R134 to check for leaks. But we cant find any unless we have a ground for the AC to turn on in the first place. ?

It doesn't go hot. It just does not turn on. Once manually grounded it Blows Cold.

 

Do you have a SnapOn MT2500? If so, what is the AC pressure? If the pressure is above minimum and the system doesn't turn on then there is an electricl problem. The reason I'm asking this is the PCM relies on this reading to know it can safely turn on the compressor. The AC request simply indicates that you have the switch in an AC position....it doesn't indicate that the system is trying to turn on at all.

By grounding the system you bypass everything and have only learned tat if the system where to turn on it would blow cold air...

 

Have you scanned the PCM for codes?

You may want to pull your pcm fuse or disconnect the battery for a bit and then reconnect. If there is a code that is causing the PCM to not send the signal to the relay, this may fix your issue.