Climate Servo II in a 1980 300D here. It sucks because it blows.

The fan blows on high even in the off position. The servo is working in the other modes, but it seems as if the defrost override mode is stuck on. Any ideas??

Allright then, I guess I will head over to Benzworld.org.

David,

Find the two pole defrost relay (on my 79 300SD it is behind the glove box). pull it out and see if the fan stops. That relay is only rated for 15 amps and runs quite hot when the AC is put into defrost. I had to replace mine in the 79 300SD.

For the same reason, the pushbutton units start to melt down over time and there could be a short there. I would avoid pulling the pushbutton unit until all other avenues were exhausted.


Jim in Phoenix

I found and pulled that relay and yes, the fan did stop. I took it to the autoparts store and when they couldn't replace it I put it back in the car, only to have the fan return to normal operation. Maybe the contacts were dirty.
Total cost for this repair - $0.00.
Hey, thanks a lot!!