When you resoldered the pushbutton controller, did you just re-heat or did you remove the old solder and apply new? I believe this is especially important for the edge connections as re-heated solder tends to separate and become very brittle.

On another note, and possibility, I have noticed that if you are having voltage problems, i.e. alternator not charging, you will also have problems with the climate control as it needs a good reference voltage to maintain a temperature. I found this out myself recently, as my alternator or possible grounding problem is causing the battery to discharge. Once it discharges enough, the CCU will not maintain temperature. After an overnight charge on the battery, everything starts working like it should. Cure your battery charging problem and you may get two birds with one stone.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )