Noise Diagnosis - Blower Motor

WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

Step	Action	Yes	No
DEFINITION: Noise originating from the blower motor.
1	Were you sent here from the HVAC Symptoms?	Go to Step 2	Go to SYMPTOMS - HVAC SYSTEMS - MANUAL or SYMPTOMS - HVAC SYSTEMS - AUTOMATIC
2	Sit inside the vehicle. Close the vehicle doors and windows. Turn ON the ignition, with the engine OFF. Cycle the blower motor through all of the speeds and modes in order to determine where and when the noise occurs. Is a noise evident during the blower operation?	Go to Step 3	Go to Step 10
3	Inspect for excessive vibration at each blower motor speed by feeling the blower case. Is excess vibration present?	Go to Step 5	Go to Step 4
4	Listen to the blower motor at each speed. Is the blower motor making a squeaking or chirping noise?	Go to Step 8	Go to Step 10
5	Remove the blower motor. Refer to Blower Motor Replacement . Inspect the blower motor for deposits of foreign material. Did you find any foreign material on the blower motor?	Go to Step 7	Go to Step 6
6	Inspect the blower motor for the following conditions: Cracked blades A loose impeller retainer Improper impeller alignment Did you find any of these conditions?	Go to Step 8	Go to Step 9
7	Remove the foreign material. Is the action complete?	Go to Step 9	-
8	Replace the blower motor. Refer to Blower Motor Replacement . Is the replacement complete?	Go to Step 10	-
9	Install the blower motor. Refer to Blower Motor Replacement . Is the action complete?	Go to Step 10	-
10	Operate the system in order to verify the repair. Does the system operate correctly?	System OK	Go to Step 2