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Noise Diagnosis - HVAC Module

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.
Noise Diagnosis - HVAC Module

Step Action Yes No
DEFINITION: Noise originating from the HVAC module.
1 Were you sent here from Symptoms or another diagnostic table? Go to Step 2  Go to Symptoms - HVAC Systems - Manual or Symptoms - HVAC Systems - Automatic
2
  1. Start the engine.
  2. Cycle through all of the following:
    • Blower motor speeds
    • HVAC Modes
    • Temperature control settings
  3. Attempt to define the type of noise:
    • Scrape, pop
    • Tick/click, chirp or groaning
    • Air rush/whistle
Is a scrape or pop noise evident when selecting modes or temperature settings?		 Go to Step 6  Go to Step 3 
3 Is a tick/click, chirping, groaning or scraping noise present, but decreases as blower motor speed is decreased? Go to Step 6  Go to Step 4 
4 Is an air rush/whistle noise evident in all modes but not all temperature settings? Go to Step 6  Go to Step 5 
5 Is an air rush/whistle noise evident only in defrost or floor mode? Go to Step 6  Go to Step 6 
6 Remove the I/P carrier. Refer to Instrument Panel (I/P) Carrier Replacement in Instrument Panel, Gages and Console.
Is the action complete?		 Go to Step 7  -
7
  1. Inspect the air flow doors for proper operation.
  2. Inspect the ducts for obstructions or foreign materials.
Were any of these conditions found?		 Go to Step 12  Go to Step 8 
8 Inspect the mode and temperature doors and seals for warping or cracking.
Are the doors in normal condition?		 Go to Step 10  Go to Step 9 
9 Replace the appropriate door and/or seals.
Is the repair complete?		 Go to Step 11  -
10 Remove any obstructions or foreign material found.
Is the action complete?		 Go to Step 11  -
11 Install the I/P carrier. Refer to Instrument Panel (I/P) Carrier Replacement in Instrument Panel, Gages and Console.
Is the action complete?		 Go to Step 12  -
12 Operate the system to verify the repair.
Did you find and correct the condition?		 System OK Go to Step 2 
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