: A/C Compressor



mjs182004
06-30-10, 09:27 AM
So yesterday I replaced my serpentine belt because the old one was on its way out.

http://i161.photobucket.com/albums/t201/mjs182004/1991%20Cadillac%20Brougham/SerpBelt.jpg

When I first got the Cadillac I ended up unplugging the A/C Compressor because it was making a whining kinda noise. I figured that I was going to use the car only in the winter, and didn't car if the A/C worked. Now though after replacing the belt, I figured why not try plugging it back in and see if the A/C even works. To my surprise it does, and it is ice cold! But my question is when I start the car, the A/C Compressor turns on right away, even when the A/C is not on and the whole system is in the off mode. Is there some kinda relay that I should be looking for?

csbuckn
06-30-10, 02:13 PM
does it turn off later?

mjs182004
06-30-10, 02:15 PM
It always is running when the engine is running. I'll see if I can make a video of it to post on here later today.

sven914
06-30-10, 03:24 PM
There are a few things that can cause the AC Compressor to run constantly. Being that our cars have a fancy computer controlled climate control system, the ECC could be malfunctioning and constantly telling the compressor to engage. To rule out the ECC as the problem, unplug the power module and see if the compressor continues to run. If the compressor stops, then one of the components of the ECC (power module, programmer, or the control head) need to be replaced. If the compressor continues to run after the ECC is disconnected, then the problem is a short to either power or ground in the compressor clutch circuit.