Mercedes-Benz W220 heater blower not running or squealing
W220 heater blower does not run, how is the fault located?
First check the 40 A fuse F35 in the right-hand fuse box under the bonnet. Then make sure the controller gets operating voltage and ground. If the motor does not run even when it gets 12 V directly at its terminals, the motor is broken. The cause can be worn-out brushes or a bearing.
Why does the blower motor squeal?
The motor shaft runs on oiled bronze bushings, and the bearings cannot be replaced separately. The squealing may stop when lubricant is added at the base of the shaft and bushings. If the noise returns, installing a new motor is usually the most practical solution.
Why does the blower get wet and how is the drain hole cleared?
If the drain hole of the air intake gets blocked, water reaches the blower and oxidises the connectors. The hole is cleared with a rod about 50 cm long, pushed in as far as the 30 cm mark. Pushing it in too deep can scratch the wing. A wet fresh-air filter should be replaced.