Hey guys, on my 1991 500SL Ive got a crazy temp control. For several weeks the buttons light up when pressed, but they dont control their function. So if I press AC the AC does not go on, if I press defrost it doesnt go on, etc etc. Sometimes they do work, but usually they dont.

Just this weekend though it really wigged out on me. The temp control shut off, there was no lights or read out on the display, and my car started to surge. I put it in neutral and the engine continued to surge, even up to 3000RPM's. Also I get hot air out of all the vents. I shut the car off and left it alone for a while and now its back to the intermittent temp control, the surging is gone. Im afraid it will come back or will cause damage to the car.

Any help would be much appreciated.

__________________
2007 Corvette Convertible Torch Red
1996 MBz SL500
2008 Harley Davidson Night Rod Special

Any check engine light or other type of warning lights?

On the 91, I believe that has the overvoltage protection relay. I don't recall having a big problem with the OVP on 129 chassis, but this sounds like a possibility in this case.

Gilly

No check engine light or anything else. The AC does work as it blows cold air, its just that the control unit will not change the fan speed or the vent location.

One thing is that when I had the surging problem the vents only blew out hot air.

So far Im thinking OVP or the CC unit itself.

__________________
2007 Corvette Convertible Torch Red
1996 MBz SL500
2008 Harley Davidson Night Rod Special