I have a 1978 300CD that keeps blowing the fuse for the blower motor. The servo unit is currently bypassed. The defroster has worked just fine until a couple of weeks ago. Now, a fuse may only last a few minutes. I'm not sure where to start looking for a short or another cause. Any help would be greatly appreciated.

 

If the fuse is blowing it is likely because the motor needs to draw too much current to get moving. Chances are the motor needs to be cleaned or rebuilt (ie: new brushes).