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Odor Diagnosis

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.
Odor Diagnosis

Step Action Yes No
DEFINITION: Odor originating or noticed through the HVAC system.
1 Were you sent here from Symptoms or another diagnostic table? Go to Step 2  Go to Symptoms - HVAC Systems - Manual or 49126
2
  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.
    • Musty smell
    • Coolant smell
    • Oil smell
Does the odor have a musty smell?		 Go to Step 3  Go to Step 8 
3 Inspect the HVAC filter and the air inlet grille for debris.
Is debris present?		 Go to Step 4  Go to Step 5 
4 Remove any debris.
Is the action complete?		 Go to Step 15  -
5 Inspect for wet carpeting.
Is the carpet wet?		 Go to Step 6  Go to Step 14 
6 Inspect for the following conditions:
  1. Water leaks around the windshield
  2. Blockage of the HVAC module drain
  3. Leaks around the door seals

Is a leak present?		 Go to Step 7  Go to Step 14 
7 Repair the leak as necessary.
Is the repair complete?		 Go to Step 15  -
8 Does the odor have a coolant smell? Go to Step 9  Go to Step 12 
9 Inspect the cooling system for leaks. Refer to Loss of Coolant in Engine Cooling.
Is a leak present?		 Go to Step 10  Go to Step 12 
10 Inspect for coolant leaking inside the vehicle or for a film build-up on the windshield.
Is the condition present?		 Go to Step 11  Go to Step 15 
11 Replace the heater core. Refer to Heater Core Replacement .
Is the repair complete?		 Go to Step 15  -
12 Does the odor have an oily smell? Go to Step 13  Go to Step 15 
13
  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 15  -
14 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 15  -
15 Operate the system in order to verify the repair.
Did you find and correct the condition?		 System OK Go to Step 2 
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