Difficult to Change HVAC Mode or Air Blows Through Upper Vents Only (Replace Foam on HVAC Mode Valve)

This bulletin is being revised to add the 2005 model year. Please discard Corporate Bulletin Number 03-01-38-005C (Section 01 -- HVAC).

Some customers may comment of difficulty in changing the HVAC (heating, ventilation and air conditioning) mode or that air blows through the upper vents only.

This condition may be caused by the foam on the HVAC mode valve (mode door) coming loose.

Technicians are to replace the foam on the HVAC mode valve (mode door) using the following procedure:

For Chevrolet Vehicles

1. Remove both instrument panel outer trim covers. Refer to the Instrument Panel (I/P) Outer Trim Cover Replacement Chevrolet procedure in SI (Document ID #874755).
2. Remove the instrument panel trim pad. Refer to the Trim Pad Replacement-Instrument Panel (I/P) Chevrolet procedure in SI (Document ID #831881).
3. Remove the instrument panel accessory trim plate. Refer to the Trim Plate Replacement-Instrument Panel (I/P) Accessory Chevrolet procedure in SI (Document ID #831885).
4. Remove the air distributor duct. Refer to the Air Distributor Duct Replacement Chevrolet procedure in SI (Document ID #646956).
5. Install a new piece of foam on the mode door valve, P/N 89018656. Refer to the instruction sheet that is included with the new part for detailed foam installation instructions and part illustrations.
6. Install the air distributor duct. Refer to the Air Distributor Duct Replacement Chevrolet procedure in SI (Document ID #646956).
7. Install the instrument panel accessory trim plate. Refer to the Trim Plate Replacement-Instrument Panel (I/P) Accessory Chevrolet procedure in SI (Document ID #831885).
8. Install the instrument panel trim pad. Refer to the Trim Pad Replacement-Instrument Panel (I/P) Chevrolet procedure in SI (Document ID #831881).
9. Install both instrument panel outer trim covers. Refer to the Instrument Panel (I/P) Outer Trim Cover Replacement Chevrolet procedure in SI (Document ID #874755).
10. Verify proper operation of the HVAC system.

For Pontiac Vehicles

1. Remove both instrument panel outer trim covers. Refer to the Instrument Panel (I/P) Outer Trim Cover Replacement Pontiac procedure in SI (Document ID #889992).
2. Remove the instrument panel upper trim pad. Refer to the Trim Pad Replacement-Instrument Panel (I/P) Upper Pontiac procedure in SI (Document ID #875317).
3. Remove the instrument panel accessory trim plate. Refer to the Trim Plate Replacement-Instrument Panel (I/P) Accessory Pontiac procedure in SI (Document ID #874606).
4. Remove the instrument panel trim pad. Refer to the Trim Pad Replacement-Instrument Panel (I/P) Pontiac in SI (Document ID #831884).
5. Remove the air distributor duct. Refer to the Air Distributor Duct Replacement Pontiac procedure in SI (Document ID #646957).
6. Install a new piece of foam on the mode door valve, P/N 89018656. Refer to the instruction sheet that is included with the new part for detailed foam installation instructions and part illustrations.
7. Install the air distributor duct. Refer to the Air Distributor Duct Replacement Pontiac procedure in SI (Document ID #646957).
8. Install the instrument panel trim pad. Refer to the Trim Pad Replacement-Instrument Panel (I/P) Pontiac in SI (Document ID #831884).
9. Install the instrument panel accessory trim plate. Refer to the Trim Plate Replacement-Instrument Panel (I/P) Accessory Pontiac procedure in SI (Document ID #874606).
10. Install the instrument panel upper trim pad. Refer to the Trim Pad Replacement-Instrument Panel (I/P) Upper Pontiac procedure in SI (Document ID #875317).
11. Install both instrument panel outer trim covers. Refer to the Instrument Panel (I/P) Outer Trim Cover Replacement Pontiac procedure in SI (Document ID #889992).
12. Verify proper operation of the HVAC system.

For vehicles repaired under warranty, use: