Blower motor stopped working 2 weeks ago after it was warm outside. yesterday night, it was 20F out, and it worked again. Today, 50F, and doesn't work again. Already checked fuse, not it. Possible culprits?

-91 300D

Check your CCU and your sniffer (the thing that controls your automatics) mine was disconnected and raised the same problems. As far as the CCU goes, look at the past threads on re-soldering the unit. Resolved most of my problems but not all. Good luck

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85 300CD The FryrBird MY daily driver

Does the CCU independently control blower motor function as well? When I click on heat, the valve correctly opens, so I know that part of the CCU works.

Brushes?

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1976 BMW 2002- 100k
1995 BMW 325i 175k
1984 Mercedes Benz 300D Turbo Diesel- 270,000 mi

1981 Mercedes Benz 240D- Estimated 300,000+ mi Returned to the earth

Push the defrost button, blower should come on high. On auto fan in heating mode I don't believe that the blower will come on until the engine is warm (water temp sensor).
If it works properly on high/defrost, then it is likely either the ccu or the blower speed controller "porcupine", under the blower (a ***** to R&R).

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Gone to the dark side

- Jeff