AC quit working last week. Worked perfectly one day, didn't the next. Compressor is not turning on. Got 12V on one side of the cycle switch, jumped across it to try to run the comp, it still won't turn on. Pulled the plug at the comp, there is no voltage at the comp harness. At first I had suspected a bad comp clutch, but the lack of voltage there would point to something else. Checked ALL the fuses, even the ones having nothing to do with the AC, all are good. Any ideas?

 

checked relays? not sure on the 99' though

 

Every time this has happened to me, it has been the fuse in the engine bay. I've had the exact same thing happen a couple times now. I can't remember which one it is off of the top of my head, but if you look at the listing of the fuses on the bottom of the lid, it's there.

 

Still has me stumped. All the fuses are good, and the relay for the AC is OK. Any more thoughts?

 

so the relay is operating? have you checked continuity in the harness?

 

Yes and yes. I'm now thinking that it's empty of refrigerant. Though it's odd that it worked properly one day, nothing the next.

 

Quote:

Originally Posted by mrclean

Though it's odd that it worked properly one day, nothing the next.

Not really that odd when it comes to the ac system since one weak link along the vast expanse of tubing and valves will cause the refrigerant to escape right quick and give you an "all or nothing" from one day to the next.

By chance were you working in or around any AC components recently (?) cause I had this happen long ago on 89 chevy crapalier - while trying to get at the water pump, I was constantly pushing against the AC lines...next day noticed the ac wouldn't work and sure enough I caused a stress crack to form in the aluminum tubing...ahhh the ignorance of (my) youth!

 

It's possible that you had just enough refrigerant one day and just enough leaked out to cause the compressor to not kick on.
If that's the case you could probably get her coolin with less than one can.

 

How are you checking that the fuses are good? May sound like a stupid question but I have had one break, not blow. It drove me nuts for two days. I visually inspected every fuse and they looked fine. But everything off the ignition switch would not work - no start, no wipers, no signal lights, no radio, etc. Everything that was independent of the ign switch worked fine - head lights, dome lights, etc. Then I got in and shut the door hard, and for a split second everything worked on the ignition switch but as soon as I tried to start the truck, nothing. Took another look at the ign (I forget the actual name and number) fuse under a magnifying glass and sure enough there was a hairline crack at the "t". If I tilted the fuse one way it was clearly open. If I tilted it the other way you couldn't tell anything was wrong with it. On the verge of having it towed, I replaced the fuse and all was well.
What got me was that it showed continuity with my test light until I turned the key on. Everytime I shut the door that would jolt the fuse enough so my test light would light but as soon as I put a load on it, bingo the fuse would fail with no visible sign of failure.