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

or

Go to Symptoms - HVAC Systems - Automatic

2

Important: A crinkle noise during mode valve recalibration is normal. Recalibration could occur when the ignition switch is OFF.

  1. Start the engine.
  2. Cycle through all of the following:
  3. • Blower motor speeds
    • HVAC modes
    • Temperature control settings
  4. Determine the location of noise:
  5. • Recirculation door
    • Temperature door
    • Mode valve

Is noise evident when selecting recirculation?

Go to Step 6

Go to Step 3

3

Is noise evident when selecting temperature?

Go to Step 6

Go to Step 4

4

Is noise evident when selecting mode ?

Go to Step 5

Go to Step 2

5

  1. Remove HVAC module. Refer to HVAC Module Assembly Replacement .
  2. Inspect mode valve for dust, dirt or debris.

Is dust, dirt or debris present?

Go to Step 11

Go to Step 12

6

Remove the HVAC module. Refer to HVAC Module Assembly Replacement .

Is action complete?

Go to Step 7

--

7

  1. Inspect the air flow door 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 air flow door for warping or cracking.

Is air flow door in normal condition?

Go to Step 13

Go to Step 9

9

Replace air flow door .

Is repair complete?

Go to Step 13

--

10

Remove any obstructions or foreign material found.

Is action complete?

Go to Step 13

--

11

Vacuum and remove dust, dirt and debris.

Is action complete?

Go to Step 14

--

12

Replace mode valve. Refer to Mode Valve Assembly Replacement .

Is action complete?

Go to Step 14

--

13

Install HVAC Module. Refer to HVAC Module Assembly Replacement .

Is action complete?

Go to Step 14

--

14

Operate the system to verify the repair.

Did you find and correct the condition?

System OK

Go to Step 2