GM Service Manual Online
For 1990-2009 cars only

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

2

  1. Start the engine.
  2. Cycle through all of the following:
  3. • Blower motor speeds
    • HVAC modes
    • Temperature control settings
  4. Determine the type of noise:
  5. • 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 Noise Diagnosis - Blower Motor

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 center air outlet duct. Refer to Center Air Outlet Duct Replacement .

Is the action complete?

Go to Step 7

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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 10

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 10

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10

  1. Remove any obstructions or foreign material found.
  2. Install any components that were removed.

Is the action complete?

Go to Step 11

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11

  1. Install the center air outlet duct.
  2. Install the instrument panel (I/P) accessory trim panel. Refer to Instrument Panel Accessory Trim Plate Replacement .

Is the action complete?

Go to Step 12

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12

Operate the system to verify the repair.

Did you find and correct the condition?

System OK

Go to Step 2