Questions and Answers

Mercedes Benz Blower Motor Q. Vince, I have a 1984 Mercedes Benz 190 Diesel, 210,000 miles, 4 cylinder, 2.2 litre engine, 5 speed, power steering. It has intermittent problems with the blower motor. When using the fan for fresh or heated air and it's warm out, the fan works fine, when it's cold and I need the heat/defrost, it quits.

I've heard that the electrical relays can stick open or closed. Is this true? Even though it's an older car, I figure the chances of an electrical short are pretty small. The fuse is obviously out of the question. I figure the fan is also good otherwise it wouldn't begin working again. When it's cold, I maybe could assume that the relay is stuck open?

Before I spend a lot of money having the problem diagnosed (which it tough when the fan is working fine), I would hope I could just replace the relay first. I've had to put very little money into this car and I obviously hate to start now.

Baffled by the problem,
Jay

A. When you have an older Mercedes Benz Jay, you get used to strange electrical problems. I have a left rear window that only works when the temperature is above 45°.

There is only a Blower Motor Relay in that system. It is located behind the center of the instrument panel, on connector i27.

If it's not the relay, then it is either the blower motor itself, a good possibility, or the Automatic Climate Control unit in the dash. I would not rule out the fuses. Those fuses were famous for losing contact. In fact I replace my fuses every two years. Look at them CAREFULLY and clean the contacts on the ends and in the fuse box.