w211 blower motor problems

[Dazzler]

My fan stops and starts as it feels like.
Also will cut out straight away if turned up to full speed.
Have checked connection and all appears fine.
Don't think it's a resistor pack as all speeds work except full.
Any ideas?

 

[Steve_Perry]

Sounds like the carbon brushes of your blower motor have worn down to the point that they only make intermittent contact on the commutator.

a/c blower - Mercedes-Benz Owners' Forums

When the blower motor stopped on my C240 it turned out to be the carbon brushes on the motor itself had worn down so short that they no longer touched the motor commutator. I stretched the springs behind the brushes and the motor worked a treat and bought me another 3 years of use. After 3 years the motor failed again and I removed the motor again and got the electric motor re-brushed for £5, I think MB wanted over £100 for a new replacement motor. All worked perfectly with the rebrushed motor until I part-ex'd her for my current car.

Failure symptoms were identical... e.g. the motor would start and stop at random.

S.

 

[Dazzler]

I have proved it to be the motor but think its drawing too much current.
If you go to full speed it pulled 11v then tripped out! !
Will have to strip the old one and inspect the brushes as it could still be them at fault.