Mercedes Benz repair: heater never turns off, fan clutch, car fan


Question
QUESTION: I Have a 1976 Mercedes 450SL. the problem is that once the car is running, the heater blowers come on and continues to blow hot air while I'm driving even though I have the switches off. thank you very much
carmelo

ANSWER: somew how you have a wiring mixup take out fuse that connects to heater and reinstall a new one then check back with me

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QUESTION: Shane:
thank you I did what you said above ,and it worked.
Same car as above, But now Its over heating, the water pump was relace because it leaked, themostate was replace, and the upper and lower radiators hoses were replaced, when moving in stop and go traffic she over heats, while traveling on the highway at 60+ mph, she does not over heat. what could be wrong

Answer
your fan clutch may be going bad to check take a piece of cardboard and put it against your fan whil;e car is running it should tear it up when you reach operating temp 87 degrees after that turn off your car fan should immediately stop this is on newer benzos as far as I think you may have a megnetic fan thoogh but most heating cooliong problems come from either a. people dont realize that mb thermos open at 87 degrees and secondary fan at 100 degrees. Do yourself a favor and turn on a/c check to see if your secondary fans come on. As far as overheating 80-100 degrees is normal for a MB anything higher than 100 then its a problem.