Got a 1996 GMC Sierra for my 17 year old son two months ago and the AC which was working good just stopped working. Checked the freon and it is good. Fan works but compressor don't kick in. Wanted to check the AC relay but don't know where that is. Can someone help me out?

 

The first thing I would check would be the low pressure switch which is mounted on the accumulator. It has a plug with 2 wires going to it. You can take a small piece of wire or a paperclip and jump the 2 terminals together. If the compressor comes on and the A/C blows cold that is the culprit.

 

Tried that earlier this afternoon and nothing happened. Got up to 105 outside and we had to stop messing with it and go inside. Can't figure out why the compressor won't kick in. Any other ideas?

 

AC relay is gonna be in the engine bay. You should see a few together. Not exactly sure where but have a look. Im pretty sure it has to be electrical.

 

This might sound weird, but turn the A/C on and take something and tap the front of the compressor. I have found a few that the clutch has gotten stuck, as a matter of fact my fathers 98 Tahoe just had that happen from not using the A/C over the winter. I tapped on it once and it has been working for the last month perfectly.

 

Kept trying to find a AC wire diagram for it yesterday but couldn't find one on line. thought we could get one thru the Haynes repair manual but did not think it had one in there and the store couldn't tell us without us purchasing it if there was a good diagram we could use in it so we didn't. Went out there little while ago with a friend from work who checked all the stuff again with the same results. Pulled out the dashboard and tested the circuit but got no codes as cleared the codes when we discharged the battery. should have checked for codes first. gonna check around tomorrow with some more folks to see if any1 has any other ideas. thanks 4 the suggestions

 

Switched the control out with a new one and it worked! Parts man said lots of trucks have had the same problem. Don't know what caused it to stop but glad it is fixed now! thanks every1 for all your help and input!

 

You know I had a 98 Tahoe that did the same thing about a year ago. I don't know why I didn't remember that. As a matter of fact I saved the old swith for the *****. Oh well, glad you found it!