GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2008 🢒 Vibe - FWD 🢒 HVAC 🢒 HVAC - Manual 🢒 Odor Diagnosis

Step

Action

Yes

No

1
  1. Sit inside the vehicle.
  2. Close all of the doors and windows.
  3. Start the engine.
  4. Allow the engine idle at normal operating temperature.
  5. Select the maximum blower speed.
  6. Select the panel air outlet mode.
  7. Select the coldest temperature setting.
  8. Cycle through all of the blower speeds, modes and temperatures to define what type of odor is present.
    9. • Musty smell
    • Coolant smell
    • Oil smell

Does the odor have a musty smell?

Go to Step 2

Go to Step 8

2

Inspect the HVAC filter for debris.

Is the HVAC filter clean of debris?

Go to Step 3

Go to Step 4

3
  1. Inspect the passenger compartment filter for odor.
  2. If the filter has an odor, replace the filter.

Did you replace the filter?

Go to Step 16

Go to Step 5

4

Remove any debris from the filter.

Is the action complete?

Go to Step 16

--

5

Inspect for wet carpeting.

Is the carpet wet?

Go to Step 6

Go to Step 15

6

Inspect for the following conditions:

    • Water leaks around the windshield
    • Blockage of the HVAC module drain
    • Leaks around the door seals
    • Blockage of the plenum drain

Is a leak present?

Go to Step 7

Go to Step 15

7

Repair the leak as necessary.

Is the repair complete?

Go to Step 16

Go to Step 8

8

Does the odor have a coolant smell?

Go to Step 9

Go to Step 13

9

Inspect the cooling system for leaks. Refer to Loss of Coolant.

Is a leak present in the engine compartment?

Go to Step 10

Go to Step 11

10

Repair the coolant leak as necessary.

Is the repair complete?

Go to Step 16

--

11

Inspect for coolant leaking inside the vehicle or for a film build-up on the windshield.

Is the condition present?

Go to Step 12

Go to Step 16

12

Replace the heater core. Refer to Heater Core Replacement .

Is the repair complete?

Go to Step 16

--

13

Does the odor have an oily smell?

Go to Step 14

Go to Step 16

14
  1. Inspect the engine compartment for any leaks. Refer to the following procedures:
  2. Repair any oil leaks.

Is the repair complete?

Go to Step 16

--

15

A musty odor can be caused by mold or mildew build up on the evaporator or the heater core or inside of the HVAC module. Refer to Odor Correction .

Is the action complete?

Go to Step 16

--

16

Operate the system in order to verify the repair.

Is the repair complete?

System OK

Go to Step 1