My AC Compressor does not turn on unless I take the Compressor relay out of the relay box and put a wire in to complete the circuit. The compressor then runs fine and pumps out cold AC. What do I need to replace? I tried the another relay that is exactly the same and it made no difference.

 

Bump!

 

Sounds like you need to scan your PCM for codes. The AC compressor Relay is controlled by the PCM.

From the 1994 Helms Service Manual:

"Air Conditioning Compressor Relay
The air conditioning compressor relay is used to provide battery voltage to the compressor clutch coil. The relay is controlled by the powertrain control module (PCM) only."

Chances are you're going to see a code 61, but possibly a 66, 67, 68, 69, 70, or 71.

Depending on which code you see, would determine the next course of action. If you don't have access to a scanner, you can pull the pcm fuse for a few minutes and it will clear any codes. After doing this, you should at least temporarily return to normal AC operation. But if the problem still exists that caused the code, it will eventually return.

A common cause for a code 61 is being a little low on R134a but you'll need the proper gauge set to determine this.

 

Thank you. That was a very informative post. The R134a level is fine, that was my first thought as well, but after manually getting the compressor to turn on I checked the level. I will have to get ahold of a scan tool.

 

Once you get it scanned and you know what code you're you showing, shoot me a PM with the code and your email address and I'll scan the relavent pages from the manual and email them to you.

Not having AC this time of year sucks...

 

Replace the relay then jumper the connector going to the pressure switch on the accumulator.

Warren

 

Thanks to the 'Cat for his post. Had my A/C crap out on me--in the wonderful FL heat--and like I would do on any other car, checked the electronics, then the 134a; the gauge on the freon was in the red, it wouldn't accept any and I was thinking 'damn--compressor.' Before I did anything, read some posts, and this one sent me in the right direction.

The PCM will shut down the compressor, and in my case, did so due to low freon. I didn't even pull the codes (was in a hurry), just pulled the PCM fuse (#4 interior), let it sit for ~10 mins, put it back in and bingo--compressor back. Tried the freon again and this time it showed low & took it. What a relief.