z064ddle

I have a 92 LT1, My compressor's clutch doesn't engage when I select any button on the console. The fan is still blowing in all of the selections. The clutch will engage when I wired it directly to the battery and will blow cold air. I thought it was because the freon is low, but I added 2 pounds already. Now, it's very full.

Is there a relay or a fuse or a sensor somewhere which turned bad, that why the clutch won't engage?

Thanks

DON M

Sorry for not posting earlier as I thought some one smarter would jump in. I am a Commercial A/C Tech and don't fool with cars very much.
The first thing I would check is the low pressure sensor.
Also 2 lbs of refrigerant may not be enough to make the sensor. The system will blow really cold with a low charge, for a while. As strange as it seems the system will freeze up with a low charge, because the exspansion device cannot regulate the flow properly. If you put a gage on the low side and run the engine, the pressure should be well above 25#, with it running at 2000 rpm. with R-12, 27# converts to 32 deg which is the freezing point of water. About 30# is normal (at 2000 rpm).

z064ddle

Thanks Don....... I don't have a guage to measure the pressure, but I think it's very full. When I turned off the engine, the "off" button on the climate control blinks. Does anybody know what that means?

Thanks

Red Dwarf

Check ur mail. :cheers:

z064ddle

I finally got around to do an onboard diagnostic test on the A/C system. It reported a low freon code (09). The thing is I already filled the system with new freon, but it still doesn't work. Turned out, you have to reset your computer by pulling the negative cable for 1 minute. So, even if you fix the problem, but if you don't reset the computer, it doesn't know it.

Basically, the low pressure switch is switching the clutch on and off too often. The A/C computer (HVAC) sense the clutch (on) cycle is too short (meaning freon is low). It shuts off the clutch permanantly until the problem is corrected. The thing is, even if you put in enough freon, the A/C computer doesn't know that automatically, until you reset it. I think this is GM kind of thing....

Hope this write-up helps those who run into the same problem in the future. Especially, summer is coming up very soon......