Noise Diagnosis - Blower Motor

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 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 Symptoms or another diagnostic table?	Go to Step 2	Go to Symptoms - HVAC Systems - Manual or to Symptoms - HVAC Systems - Automatic
2	Sit inside the vehicle. Close the vehicle doors and windows. Turn ON the ignition switch, with the engine OFF. Cycle through all the blower motor speeds and modes in order to determine where noise occurs. Is the noise evident during blower operations?	Go to Step 3	Go to Step 10
3	Does the noise vary with the blower speed?	Go to Step 4	Go to Step 10
4	Inspect for excess vibration at each blower motor speed by feeling the blower case. Is excess vibration present?	Go to Step 5	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 10	-
8	Replace the blower motor. Refer to Blower Motor Replacement . Is the action 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. Did you find and correct the condition?	System OK	Go to Step 2