Blower motor oddities

[stwat]

The blower motor packed up in my 1989 300SE. So I removed it to check the conditions of the brushes. They are fine. I fed a direct power feed to the motor and it runs fine. So I checked with my meter and I have power to the fan motor connectors. Here's the odd bit. As soon as I plug them into the motor the power vanishes Unplug them, 12v. Plug them in, nothing.

Can anyone shed some light on this as it's getting bleeding cold outside.

Cheers,
Stu

 

[Druk]

Tried the fuse/ fuseholder? Corrosion can leak enough current to be detectable on a meter but not to drive the fan.

 

[stwat]

I have indeed and even tried a new fuse and all connections are corrosion free. I have power there too.

 

[Druk]

Dry joint in a relay somewhere? Would have the same effect. Or the fan earth? Try running a temp earth from the brown @ the connector to the chassis.



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[stwat]

I gave up and took it to an auto lecky I know. It turns out it is the rotary switch in the dash. Or as he calls it, the regulator. £111+ from MB but he's ordering one in and letting me have it for the trade price he gets, £77. Just waiting on it being delivered from Germany.

There were some on ebay but they're just as old as mine, so god only knows how long they would last.

I'm just happy they can still be bought from Mercedes.