Odors may be emitted from the air conditioning system primarily at start up in hot, humid climates. The following conditions may cause the odor:

When the blower motor fan is turned on, the microbial growth may release an unpleasant musty odor into the passenger compartment.

A service kit that can correct the condition is available through GMSPO to address this condition.

To remove odors of this type, it is necessary to eliminate the microbial growth and prevent its recurrence. To accomplish this, these two procedures must be completed.

The blower control package will enable the blower to run at high speed for 5 minutes. This will occur approximately 50 minutes after the ignition has been turned off if the compressor had been engaged for 4 or more minutes prior to turning off the engine. By doing so, the evaporator case and core are dried out, reducing the chances of a recurring A/C odor.

Perform the following steps in order to deodorize the A/C system:

1. Ensure that the plenum that draws outside air into the HVAC module is clear of all debris.
2. Disable the A/C compressor clutch operation by disconnecting the clutch coil electrical connector.
3. Dry the evaporator core by performing the following steps:

3.1.	Start the vehicle.

3.2.	Set the temperature control on maximum heat.

3.3.	Set the control to the MAX setting.

3.4.	Run the blower motor on high for 10 minutes.

4. Locate an area in the air conditioning duct between the blower motor and the evaporator core downstream of the blower motor.
5. Drill a 3.175 mm (0.125 in) hole where the hole will not interfere with, or damage the following components:

•	The blower motor

•	The evaporator core

•	Any other operating part the of system

6. Wear safety goggles and latex gloves in order to perform the following actions:

6.1.	Continue to operate the blower motor on high.

6.2.	Insert the extension tube of the deodorizer GM P/N 12377951 into the hole, past the mark on the extension tube.

6.3.	Use short spray bursts and vary the direction of spray for a 2-3 minute period of time, in order to dispense the contents of the can into the duct.

7. Shut the engine OFF. Allow the vehicle to sit for 3-5 minutes.
8. Seal the 3.175 mm (0.125 in) hole with body sealer or RTV gasket compound.
9. Start the engine.
10. Operate the blower motor on high for 15-20 minutes to dry.
11. Reconnect the A/C compressor clutch coil electrical connector.
12. Verify proper clutch operation.