GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 Safari - 2WD 🢒 HVAC 🢒 Heating, Ventilation and Air Conditioning 🢒 Odor Diagnosis

Step

Action

Yes

No

1
  1. Sit inside the vehicle.
  2. Close all doors and windows.
  3. Start the engine .
  4. Let the engine idle at normal operating temperature.
  5. Select the high blower speed.
  6. Select the VENT 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 5

2
  1. Inspect the evaporator drain tube for a blockage.
  2. Clean and repair the blockage as necessary.

Was the drain plugged and an excessive amount of water present?

Go to Step 3

Go to Step 4

3
  1. Inspect for any water leaks at the plenum to cowl.
  2. Inspect the HVAC filter and cover for debris.
  3. Inspect for wet carpeting.
  4. Inspect for wet floor mats.

Did you complete the repair?

Go to Step 12

--

4

A musty odor can be caused by mold/mildew build up within the HVAC module, the evaporator or heater core. To correct the odor refer to Odor Correction .

Did you complete the repair?

Go to Step 12

--

5

Does the odor have a coolant smell?

Go to Step 6

Go to Step 10

6

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

Is their a leak present in the engine compartment area?

Go to Step 7

Go to Step 8

7

Repair the leak as necessary.

Did you complete the repair?

Go to Step 12

--

8

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

Is there a leak present?

Go to Step 9

Go to Step 10

9

Replace the heater core. Refer to Heater Core Replacement .

Did you complete the repair?

Go to Step 12

--

10

Does the odor have an oil smell?

Go to Step 11

11
  1. Inspect the engine compartment area for an oil leak. Refer to the following for leak diagnosis:
    2. •  Oil Leak Diagnosis in Engine Mechanical - 4.3L
    •  Fluid Leak Diagnosis in Automatic Transmission - 4L60-E
    •  Power Steering Fluid Leaks in Power Steering System
  2. Repair any oil leaks.

Did you complete the repair?

Go to Step 12

--

12

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 1