compressor craziness

[abarthle]

Hey guys, i'm havin some compressor problems and i was wondering if ya'll could shed some light on this...

I have a '94 Firebird Formula, 350 LT1 and all the sudden today i stop getting cold air. I've checked all fuses, and their good. The static pressure levels on the high and low sides when the car is off. Freon is in good shape. Now the real screwy part is i plugged in my OBD I scanner in to see if it would flash any codes, for one thing no codes flashed, the light never came on at all. However when the scanner was plugged in and the key on start, the compressor would come on, so i tried to start it up with the scanner in, and immediately the compressor turned off. For some reason the PCM or something is telling the compressor to turn off whenever the car is started. I'm not sure what to touch, whether to replace the compressor or look at getting a new PCM. The electronics have been screwy in this car since day one. I went to a dealer mechanic buddy for a free look at it, he plugged in his OBD I scanner, not just a code flasher, and he got no readings, he couldn't clear codes or change any settings what so ever.

Any idea what might be causing my electronic/compressor struggles?
i'm hopin someone has had experiance with this system and can lend any thoughts.

Thanks alot guys.

[JohnnyBs98WS6Rag]

However when the scanner was plugged in and the key on start, the compressor would come on, so i tried to start it up with the scanner in, and immediately the compressor turned off. For some reason the PCM or something is telling the compressor to turn off whenever the car is started.

First off, I'd like to know how you know the compressor is "ON" when the engine is "OFF"?? Measuring the voltage at the compressor clutch w/ the engine OFF and ignition ON?

In any case, if your compressor is cycling ON and OFF for no apparent reason, your freon is probably low. There is a pressure sensor on the suction side of the compressor, if the pressure isn't high enough it will cut-off the compressor. When the freon is low, as soon as the compressor comes on, it sucks down the pressure on the suction side too much and the switch turns the compressor OFF, then after a while when the pressure re-balances, the switch will turn the compressor back on and the cycle repeats. Checking codes won't tell you jack about the pressure in your refridgerant system, you need a R146a refill kit w/ pressure guage. Re-charge it and you should be golden.

[abarthle]

i've checked the freon with gages, and as i said in my post it's fine, 110 psi on high and low side. i'm thinking its the ECM, cuz i've never been able to get any codes from the computer and it's just been screwy since day 1 so my thinking is the kid i bought it from prob tried to either chip it or used something on the computer and screwed somethin up in there.

any more suggestions?

[abarthle]

hey i got it fixed, i grounded the relay in the fuse box with the car running and there the compressor turned on and had cold air, so i concluded it was the computer's fault for not grounding it. i pulled out sensor on AC lines and disconnected computer sprayed WD40 on the contacts and reconnected the computer and AC sensor and bam ice cold air.

thanks anyways guys.

[Cheviac2K]

So you're getting 12s from the ECM now? If not I'd keep the investigation open.

[abarthle]

actually i'm not, still getting no codes from the computer and my air bag light randomly came on. Perhaps i should just look around on the internet for a new computer and be done with it. Obviously it's having problems with some things so i should just replace the piece of crap.