Adam, Harry, Larry, Dpetryk... I pulled the entire plastic unit out of the dash. Took off the top row of buttons(Rear deck light etc) and pulled the 2 electrical plugs out of the ccu. I took 4 small screws off the thin, plastic bottom plate. There exposed was a green circuit board. I could redo all of these solders but are there more? There seems to be another board deeper. Do I need to access it? How do I get the green one out? Do I have to pull the temperature wheel off to get both boards out? I do not see where the pushbuttons solders are now.

I did check the ccontinuity between the pins for the plugs and the green circuit board.

My local library has internet access to Mitchell's. Will they have good info. Does the MB shop manual have an effective algorithm to check all parts of the HVAC system? Is there any detailed source on line?

Many thanks to all.