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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53016
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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The blower won't run. It cut out then on then off. Now off

Customer Question

The blower won't run. It cut out then on then off. Now off for completely
JA: What is the model/year of your Mercedes?
Customer: 1992 300E
JA: Are you fixing your 300E yourself? What have you tried so far?
Customer: Fuses. All seem ok
JA: Have you checked the vehicle's manual yet?
Customer: Yes
JA: Anything else you want the mechanic to know before I connect you?
Customer: Heat present in vents and cold present in vents. Just can't circulate out
Submitted: 1 month ago.
Category: Mercedes
Expert:  Marty replied 1 month ago.

Hi, my name is***** problem will either be a bad blower motor fuse or a bad blower motor or blower regulator. The blower fuse is not in the main fuse box. The fuse is located in a separate fuse box located in front of the main fuse box. If that fuse is good you will need to replace the blower motor and the regulator.

Expert:  Marty replied 1 month ago.

Let me know if you need anything else. Don't forget to rate my service in order for the website to credit me for helping you.

Customer: replied 1 month ago.
I said I checked the fuses. I know about the external fuse box and checked them.
I don't agree. The blower bounces on and off sometimes a week between sometimes month. Seems like a short or loose wire somewhere.
Expert:  Marty replied 1 month ago.

Most people don't know about the separate blower fuse. The reason the blower cuts in and out is because the brushes in the motor are worn out and barely making contact.

Expert:  Marty replied 1 month ago.

If you have a voltmeter or test light I can tell you how to test the circuit but you need to test it when the motor is not working.

Expert:  Marty replied 1 month ago.

Also make sure that the strip fuse doesn't have a hairline crack in the center of it.

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