I have a 96 GC LTD, W 5.2L V8 the AC has been blowing luke warm air. I'm not really sure how to check the compressor for sure, but when you turn on the button inside the pitch of the engine changes. I also checked the fuses, all seem to be fine. So, I thought maybe it needed refrig. so I bought a can with gauges. Hooked up to the low pressure side, very little to no pressure. I empty the can in the system, now I'm getting around 10 psi, and still no cold air. Any suggestions? How do you test the compressor?

 

Pitch of the engine changes because the compressor is turning on.. Rpm's will go up a little with the a/c on also.

Did yo check the PSI with the engine on ?

 

Yes, I did check the pressure with the engine running, and the ac on max.