smokey

Just thought I'd pass this on, and thank Rennlisters for the lead. I'd been having problems with the AC/heating controls on my 951 since I got the car four years ago. Had tried four different used control units, and had a number of mechanics try to fix it. It would work for a while, and then the heater would turn on full blast - usually as I was entering turn 4 at Mosport. Did all the diagnostic tests in the manual, everything checked out. The system would work perfectly when the engine was cold. The "clip" was ok. Yesterday, I took out the glove compartment to check the operation, and I saw that the ground cable from one of the solenoids was connected to the dashboard support with a very rusted self-tapping screw. Don't know whether this was an original ground or had been added at some point. I replaced the screw with a stainless one, sanded all the connecting surfaces, and took it out for a test drive. Problem solved - I think. Anyway, for anyone with an erratic AC/heating system, check out this ground wire.