Mercedes-Benz W202 heater blower does not run or speed varies
Mercedes-Benz W202 heater blower does not run or runs randomly, what is the fault?
The most common causes are the series resistor, worn brushes in the blower motor, an oxidised fuse or weak solder joints in the climate control panel. First check the fuses and try the motor with direct power, so you can see whether the fault is in the motor or in the control.
The blower runs only at full speed or all speeds work the same. What is the cause?
The fault is typically in the series resistor (dropping resistor), which is located in the front passenger footwell. When it fails, the blower either stops working or always runs at full speed. If replacing the resistor does not help, check the control panel's solder joints and potentiometers.
How do I service the blower motor brushes and what wears them?
The motor is in the front passenger footwell and new brushes are easy to fit. No grease may be put on the brushes or the commutator, because it softens the brushes. The drain pipes of the windscreen scuttle channel should be cleaned a couple of times a year so that water does not collect in the blower housing.
Blower output weakens although it runs. What do I check first?
Check the cabin air filter under the glovebox, since it can be clogged even if it does not look like it from above.