ok I will check the Aux pump next. Upon further inspection last night, I found that the clicking is actually a relay back in the console and NOT the climate control unit itself. It sounds like an erratic effort by the climate control to attain the proper temp setting but it becomes confused as you slowly roll the temp dial.

After pulling the unit apart and plugging it back in, the night time display lights are working on it once again on the temp wheel and pushbuttons... strange.

Are these newer 126's still wired up in such a fashion that the Aux pump can take out the CCU?

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(2) 1988 300 SEL W126