Odor Correction

Odor Correction

Musty Smell

1. Check for water leaks.
2. Repair as necessary.
3. Check evaporator drain for blockage. Clean as necessary.

Under certain climate and operating conditions, a musty odor develops from mold growth in the evaporator core face. This odor is generally temporary. As climate conditions change, the condition will repair on its own. However, if the odor persists, remove the evaporator core and clean the face with an appropriate cleaner.

Odors may be emitted from the air conditioning system primarily at startup in hot, humid climates. This odor may be the result of debris in the heater/A/C evaporator case or growth of mold on the A/C evaporator core.

Cleaning Procedure

Tools Required
* J 36645 Air Conditioning Cleaning Gun
* GM Goodwrench Air Conditioning System Disinfectant Kit

Caution: Procedure should only be performed on a cold vehicle to prevent the disinfectant from coming in contact with hot engine components. Disinfectant can cause substantial but temporary eye injury. Do not get in eyes or clothing. Wash thoroughly with soap and water after handling.

Important: Complete the following steps if disinfectant gets into your eyes:


1. Hold your eyelids open.

2. Flush your eyes with a steady, gentle stream of water for 15 minutes.

3. Obtain medical attention if the irritation persists.


1. Put on rubber gloves and safety goggles.
2. Pour the small bottle of the two-part GM Goodwrench Air Conditioning System Disinfectant Kit into the large bottle.
3. Seal the container.
4. Invert the large container 1-2 times in order to mix the contents.
5. Inspect underneath the vehicle in order to verify that the drain outlet is not plugged.
6. Connect the battery charger in order to avoid draining the battery during the cleaning procedure.
7. Remove the blower resistor. Leave the wiring connectors attached. Refer to Blower Motor Resistor Replacement Service and Repair.

Notice: Do not allow the metal coils of the blower resistor to become grounded to any metal surface as this may result in internal circuitry damage.

8. Inspect the heater/A/C evaporator case for debris.

* Remove any debris that is present through the blower motor resistor opening.
* If the debris is embedded into the A/C evaporator core face and cannot be removed, remove and clean the core.
* If a large amount of debris is present in the heater/A/C evaporator case, seal the air inlet screen around the air intake in the cowl area.

9. Turn the ignition to the ON position. Do not start the vehicle.
10. Set the mode selector to VENT.
11. Set the blower speed to LO.
12. Set the temperature to full COLD.
13. Open all of the windows and the doors.
14. Exit the vehicle.
15. Place a drain pan with at least a 2-quart capacity below the heater/A/C evaporator drain hole. Position the drain pan so that it will collect the disinfectant and rinse water runoff. If necessary, install an additional hose onto the drain so that all of the fluid goes into the drain pan.
16. Turn the pedestal fan to HIGH in order to provide cross ventilation during the cleaning procedure.

Important: Do not allow disinfectant to come into contact with any hot engine components, such as the exhaust manifold.


17. Insert the nozzle of the J 36645 , or an equivalent spray gun, through the blower motor resistor opening. Insert the siphon hose into the container of disinfectant.
18. Spray the disinfectant directly toward the A/C evaporator face.

1. Saturate the core completely.
2. Use the entire container of solution.
3. Be sure to cover the corners and the edges.

19. Turn the ignition to the OFF position.
20. Allow the core to soak for 5 minutes.
21. Inspect underneath the vehicle. Verify that the drain is operating properly. If necessary, use a razor blade or a sharp knife in order to unclog and increase the drain plug slits.
22. Turn the ignition to the ON position. Do not start the vehicle.
23. Use the spray gun in order to thoroughly rinse the A/C evaporator core with clean water. Remove all of the disinfectant residue. Use at least 1-2 liters of rinse water.
24. Turn the ignition to the OFF position.
25. Reinstall the blower motor resistor. Refer to Blower Motor Resistor Replacement Service and Repair.
26. Dispose of the disinfectant and the rinse water that was collected in the drained pan. Dispose of the liquid in an approved manner.