IMPORTANT NOTICE – PLEASE READ
The control unit can fail for no apparent reason but it may also fail due to excessive load by the blower motor.
It is usually either because of a blocked pollen /air filter or because rain water has got into the blower motor.
The danger is that if the motor has had water in it then it could be partially seized which in turn may cause the repaired unit to fail prematurely.
IMPORTANT STEPS TO CHECK FIRST BEFORE FITTING THE REPAIRED UNIT
1. Check the condition of the pollen / air filter - Not all cars have them but it is worth checking for a pollen / air filter on the air inlet to the motor. On most cars the air inlet is located under the bonnet directly by the windscreen area.
2. Check for any blocked rain water drain points - Make sure that rain water is not collecting around the air inlet to the blower motor.
3. Check that the blower motor is not seized - If you can get your hand into the motor then check it turns freely. For safety it is important the key is out of the ignition before putting your hand into the motor.