Not sure, Bill. I don't have any experience with the servos and frankly, plan to stay away from any cars so equipped. I see that Performance products has a solid-state control system to replace the servo completely...only $600!

I will say that the fans on my W123s will blow at high speed in all modes.

Since you seem to be drawing a blank in this thread, maybe you want to start a new one under a different title. Did you see the thread on this Bentley forum?
http://tech.bentleypublishers.com/category.jspa?categoryName=mercedes-benz

Hmm....I wasn't aware Bentley even published manuals for Mercedes, let alone the W123.

Russ