A/c diagram

[mytrplseven]

Anyone know where I can get an A/C electric diagram for the '86 944 Turbo? I'm trying to isolate the problem but I'm shooting in the dark. The compressor isn't getting any volts so I'm working backwards from there.

[944 Ecology]

[mytrplseven]

Thank you, George. I still don't have volts to my compressor. I jumpered the low press switch to see if that was the problem but it still didn't have any volts. The system is pressurized, the compressor and hoses are new and it worked for a month and now it's devoid of any volts to run the compressor. The cooling fans do come on when a/c is selected so I'm at a point of head scratching. I wish I had another a/c relay (g-7) to swap it out but I don't. replacement in next week.

[kdjones2000]

This can burn out if the clutch coil is shorted or drawing too much current.

[944 Ecology]

Originally Posted by kdjones2000

This can burn out if the clutch coil is shorted or drawing too much current.

Yes, that is an unfused circuit. I recommend installing a 10 amp fuse inline to that circuit.

[mytrplseven]

I wish I had a better handle on this instead of just replacing one component after another. The compressor and clutch are new OEM units so I'm at a loss as to what's the best course of investigation. I have a new a/c relay on it's way for starters. Good thing, though, while I was under the car I saw the upper compressor mounting bolt falling out. Cleaned the bolt with brush and brake cleaner and then coated it with Blue locktite before replacing it.

An inline fuse for that circuit sounds like a good idea. I couldn't figure why Porsche would not protect it with a fuse somewhere on that line.

[Jfrahm]

The AC button can fail as can the AC relay. There is a fuse for the AC compressor clutch I believe. Simple test plan would be to:
Check AC pressure - if no pressure no compressor, stop and find the leak.
If there is pressure hotwire the compressor and see if the clutch works
Check the fuse and power at the fuse
Check/bypass the pressure switch
Check the button, these were replaceable on later CC heads as I think they tend to die, soldered-in on the 86.
Check the relay Bypass as needed.

You say it worked for a month, usually that means the gas has leaked out. However in an 86 I'd also suspect the button on the CC head.

Good catch on the upper AC bolt. People wreck those AC mounts and strip those bolts by not loosening things properly when adjusting belts.

-Joel.

[mytrplseven]

Well, I ran direct 12 volts to the compressor clutch through the a/c relay, pressure switch and it all worked. Now on to the climate control unit and therein lies my new problem. I can't lay my hands on an electric diagram for the controller. All the diagrams seem to avoid showing the actual a/c off and on switch and other internal circuitry. If anyone has more to offer on this, I'd be grateful for the help.