86 740 Turbo A/C problem

cosmiclobster · Post by **cosmiclobster** » 29 Aug 2005, 17:25

HELP!!! I have a problem with my A/C.

The pressure switch on the dryer/condenser is always open circuit. Since this switch is in series with the compressor clutch, the compressor never engages and the A/C doesn't work. There is 12V on one side of the switch.

SO, I bypassed the switch with a piece of wire to test it, stared the car and
now the clutch engages but switches on and off every second.
Does this sound familiar to anyone??? Any ideas why my clutch is neurotic?
Is this a pressure problem? I know that there is some pressure in the system because I found a valve and let a tiny bit out!
I suspect that the clutch is good because when I apply 12V with the engine stopped, it does pull in.
I also know that the compressor is not seized because I can turn it with my hands

Any help would be greatly appreciated!!

petershen1984 · Post by **petershen1984** » 30 Aug 2005, 19:00

Hello.

The compressor cycling on and off is actually a symptom of low refrigerant. You could validate it by just giving it a little charge of coolant. If the compressor runs and the cabin begins to cool, all that's left is to trace the leak and replace the appropriate tubes.

One caveat is that now you may have to retrofit the whole system to the R134a refrigerant coolant.

cosmiclobster · Post by **cosmiclobster** » 31 Aug 2005, 01:07

Actually, I had just today come to the conclusion that giving it a charge was my next step! (or at least putting a guage on it to see how much pressure is in there)
I discovered an adjustment screw on the pressure sensor that connects to the receiver/drier. By adjusting it I was at least able to get the compressor clutch to engage. I'll worry about setting it to the correct pressure after I feel the first blast of cool air!!!

Thanks for your help!