GM Service Manual Online
For 1990-2009 cars only

Musty Smell

Problem

Action

Water leaks in the body are present.

Seal the body.

The evaporator drain is dirty or clogged.

Clean the evaporator drain.

Mold or mildew is present in the evaporator¹.

Clean the evaporator.

¹ A musty odor will develop under certain climate and operating conditions. The musty odor is caused by microbial growth in the evaporator core. This odor is usually temporary. As a climate conditions change, the musty odor will usually disappear. If the odor persists, clean the evaporator core using an appropriate cleaner. Refer to Odor Correction

Refrigerant Oil Smell

Problem

Action

The evaporator is leaking.

Replace the evaporator core. Refer to Air Conditioning Evaporator Core Replacement

Coolant Smell

Problem

Action

The heater core is leaking.

Replace the heater core. Refer to Heater Core Replacement

The heater core pipes or hoses are leaking.

Replace the heater pipes or hoses. Refer to the appropriate procedure: