Just wanted to update with regards to my a/c problem on 1980 300d. I replaced a/c servo with junkyard find and that fixed my heat to cold problem. Now I can dial in heat or have cold. This is a good thing.

The last remaining problem is that pushbuttons only work when I give the foot pedel a little more trottle. I know that vacuum increases when I do this causing the buttons selected to activate pods. Definitely have a leak.
I have tested all pods and there all good now. I replace one. How do you test switches? Yellow, green, and brass looking ones? I vac on them and hear them click and they hold vac. Is that good enough?

The part that confuses me about this system is the controlled leaks. So, when testing with mityvac you really got to know when your testing an area that should leak down. Make any sense? Should green line at engine leak at all? Should it hold for 5 minutes? Lost here! Car shuts down and door locks work.

When I mityvac the green line at engine I hold no vacuum. I can hear hissing at the pushbuttons when I vac the green line. I figure that the buttons need to be replaced. The part at MB is $140. I have another set of junkyard buttons that do the same thing.

Well, I guess I am officially sick and tired of thinking about this climate control thing. 2 weeks and counting. I really would like to put back center console soon.
Any comments will be much appreciated.