There is a potentiometer located in a hard to get to place that tells the control module the location of the flaps. The pot is located under the dash pad. The good news is that it can be diagnosed without pulling the dash pad. The bad news? It can't be replaced without pulling the dash pad. Also there is a vac line that runs under the battery tray on some 190's and they will crack and leak. This will cause many different problems.
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