AC Help on a 90

07-12-01, 01:51 PM

I have a 90 Corvette in the shop, we are doing some exhaust work, paint work and AC Work. The problem comes with the AC work, it was low on freon and the compresser would not come on. I thought will, it's low on freon therefore it will not come on. So, I went ahead and converted it to 134A and the compressor will still not come on. I have check the fuse at the fuse block, and have checked it at the low pressure, high pressure, and some other switch on the high side and have no voltage to any of them. Is there another fuse or switch somwhere or could the problem be in the controls..........Thanks for your help........Steve

69MyWay · 07-12-01, 04:01 PM

I had this same problem and did just about the same thing as you.

Turns out that the CCM saves a memory of how often the compressor cycles in a given amount of time. As a saftey function it will shut down all power to the compressor/clutch when it determines it is cycling too frequently. Obviously the old R-12 system had a leak and it had cycled once too often/too fast.

All you have to do is disconnect the battery for a minute or so. Some suggest grounding the positive lead to the frame for 10 seconds.

Cadillac has this same fail safe system. I learned the trick from a jobber source for a/c parts and supplies.

Let us know if it works.

Chris

69MyWay · 07-12-01, 04:48 PM

I hope I did not sound confusing.

I meant disconnect the battery all together. Pull the positive lead off the battery and touch the positive lead cable to a source of ground for 10 seconds. Then reconnect the positive terminal lead to the battery.

Start the car back and turn on the a/c. It should start working fine.

Does that make more sense? I read my reply and realized it sounded like I was suggesting grounding the positive terminal. That would be bad.

Chris

Ken · 07-12-01, 07:03 PM

Quote:

Originally posted by Chris McDonald
I read my reply and realized it sounded like I was suggesting grounding the positive terminal.

I understood, Chris.

Ken

07-12-01, 09:07 PM

Chris, I didn't really understand until the I read the second post, but I knew you couldn't mean what it sounded like you meant (does this make any sense). It is hard to try and type somthing and explain it, ain't it

Hey, it work just as you said though. I just disconeected the negative side of the battery, waited a few minutes and wha-la the AC works. Boy, these cars are getting way too smart

Thanks a lot Chris..............Steve