Blower Motor: Testing and Inspection

POSSIBLE CAUSES
Possible causes of an inoperative blower motor include:
- Faulty fuse
- Faulty blower motor relay
- Faulty blower motor battery feed circuit
- Faulty blower motor ground circuit
- Faulty blower motor resistor
- Faulty blower motor switch
- Faulty heater-A/C mode control switch
- Faulty blower motor.

Possible causes of the blower motor not operating in all speeds include:
- Faulty fuse
- Faulty blower motor relay
- Faulty blower motor battery feed circuit
- Faulty blower motor resistor
- Faulty blower motor switch.

Vibration
Possible causes of blower motor vibration include:
- Improper blower motor mounting
- Improper blower wheel mounting
- Blower wheel out of balance or bent
- Blower motor faulty

Noise
To verify that the blower is the source of the noise, unplug the blower motor wire harness connector and operate the heater-A/C system. If the noise goes away possible causes include:
- Foreign material in the heater-A/C housing
- Improper blower motor mounting
- Improper blower wheel mounting
- Blower motor faulty