Diagnosis And Testing - Blower Motor: Noise

To determine if the blower motor is the source of the noise, simply switch the blower motor on and off. To verify that the blower motor is the source of the noise, unplug the blower motor wire harness connector and operate the heating and A/C system. If the noise goes away, possible causes include:

• Deformed or damaged blower wheel
• Foreign material in blower wheel
• Foreign material in the HVAC housing
• Foreign material on fresh air inlet screen
• Improper blower motor mounting
• Worn blower motor bearings or brushes