GM Service Manual Online
For 1990-2009 cars only

Condition

Correction

Important: Under certain high humidity climate operating conditions, a musty odor may develop. The odor develops due to microbial growth in the evaporator area. This odor is generally temporary. As the climate conditions change, the condition will disappear. If the mold/mildew odor persists refer to the Odor Correction procedure.

A musty odor

    • Mold/mildew growth exists in the evaporator fins. Clean the evaporator fins. Refer to Odor Correction and/or Air Conditioning Evaporator Core Replacement .
    • The evaporator drain is clogged. Clean the evaporator drain.
    • Interior water leaks exist in the body. Seal the body. Refer to Generalized Testing and Body Waterleak Repair in Waterleaks.

A coolant odor

A coolant leak exists. Inspect the heater hoses and the heater core for leakage. Refer to Heater Core Replacement and Heater Hoses Replacement .

A refrigerant oil odor

A refrigerant leak exists in the evaporator. Inspect the evaporator and the fittings for refrigerant leaks. Refer to Leak Testing .