mine's an '85 and appears to be a different animal. Next time I get rountoit...I'll look a little closer. I don't believe the sensor in my case is vac. related. Were I to guess, it either monitors coolant temp for aux. fan operation, or has something to do with prohibiting too early use of heat??? Just guessing at this stage...Thanks again.

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Rob M
Norwich, VT USA
1980 240D Euro delivery 4 speed manual silver/blue
~160K miles