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1995 993 HVAC control unit hum

Heating and Ventilation

Vehicle Information: Year: 1995; Body Type: Convertible; Total Mileage: 42,500;

I have the same humming noise coming from HVAC unit as mentioned by two other people. Last week I had the car in for routine maintence and asked about the humming noise when the car is turned off. My mechanic at EuroMotor Works in Indianapolis informed me that this is common on some 993's. He said it was a very small DC motor still energized in the control unit that samples the cabin air and outside air for the correct mixture in the cabin. He said do not worry about it, especially since the heating and A/C still work correctly. The noise still bugs me, however I will learn to live with it.

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