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Discussion Starter #1
my friend has a 1992 cadillac deville that he took in for service and came back with the a/c service light on and the a/c not working. It still has refrigerant pressure - the shop would check for pressure but doesn't deal with r12 anymore so they wouldn't evacuate and charge it for him. When you set the climate control to automatic and a low temperature like 60 (it's 85-90 outside) it changes to economy mode and the amber 'service a/c system' light is illuminated for 10-20 seconds and goes off once it switches to econ mode.

Since it still showed pressure, what will cause it from engaging the clutch?

Should I be able to measure a current at the a/c clutch connection?

I replaced the under-dash fuse with a new one just in case and also tried 'hopping' the pressure switch up near the radiator with a wire to over-rule low system pressure to keep the clutch from engaging. What should I try first? Is there an in-line fuse or a relay that is common to be replaced? I saw the radiator cooling fans work fine.

Thanks a ton in advance...

Gus
 

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Gus,
You need to find out what the light is on for. Check the OBD display. You're looking for "F" codes. This will at least tell you why the compressor is being cut-off. BTW, the system can be LOW but not empty and it will still disengage the compressor.
 

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Discussion Starter #3
Got error codes...

I checked the error codes and it gives an 'F11' and a 'F47' error code. I was told that If it is a low refrigerant code, unhook the negative battery cable to clear the code and then hook up the gage manifold and refrigerant so that when the engine is started, it will pull in enough of the refrigerant to read the pressures before the code sets. :bonkers:

I'm planning on doing this - does it make sense or do you think I need to vacuum the system first then charge it like normal?

Thanks again for keeping me on the right path.

I told my friend about this forum and It sounds like he's going to sign on... It's always good to have another person to share 'past experiences' with...

Gus
 

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Re: Got error codes...

As long as you have ANY refrig. in the system, you're ok and shouldn't need to evacuate and recharge. Try a partial charge if you can find someone that has R12. In the long run you'd be better off to retrofit to R134a but that's your decision to make.
 

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Discussion Starter #5
cleared code but no clutch yet

Okay, we removed the battery cable and cleared the code. We overode both line pressure switches and the error code doesn't appear and it stays on automatic but the compressor clutch does not engage.

I checked the main fuse in the engine compartment and it was fine. There are about 5 relays under that cover as well. How can I find out which is the a/c relay? I have a manual but it doesn't spell out relay position as installed in the vehicle - or maybe I'm missing it.

Once the relay is deemed good or bad, what else could stop the clutch from turning on besides a bad wire? I'll check to make sure there is 12v on each side of the relay and thru the wire harness at the compressor but other than than is there anything else to check?

Hot in Michigan....

Gus
 

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if you don't have any refrigerent in the a/c canister the clutch won't turn on, it disables it so it doesn't burn out. i have no refrigerent in my car since i bought it and the compressor clutch hasn't worked since, soon i will recharge and retrofit the system with r134a and the compressor should kick back on no problem.
 
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