Loud Whistling Noise From Passenger Inboard Instrument Panel (I/P) Vent (Install Foam Block)

Come customers with the C67 HVAC module without the console/floor vent may comment on hearing a loud whistling noise from the passenger inboard I/P air vent. The loud whistling noise may occur when the HVAC system is in the defrost mode and the temperature setting and the fan blower speed is on high.

This condition may be due to high pressurized air flowing through a small space between the passenger inboard I/P air vent damper door and the duct housing.

Perform the following in order to determine that the above condition exists:

1. Insert the ignition key and turn the ignition switch to ON.
2. Set the HVAC controls. Refer to the above condition.
3. With the HVAC system operating, gently pull the front vertical air distribution duct that is under the I/P towards the rear of the vehicle.
4. If the whistling noise stops, GO TO the repair procedure in this bulletin.
5. If the whistling noise does NOT stop, refer to the standard diagnostic procedures in the Service Manual.

Create a pressure relief gap at the forward side of the air distribution duct housing.

The following materials are required:

1. Wrap tape that has self-sticking adhesive on both sides 2 times, side-by-side, around the foam block (1).
2. Insert the ignition key and turn the ignition switch to ON. Set the HVAC controls. Refer to the above condition.
3. Gently pull the front vertical air distribution duct that is under the instrument (2) towards the rear of the vehicle until the noise stops.
4. Install the wrapped foam block (1) on to the front surface of the front vertical air distribution duct in a position that keeps the HVAC system from whistling.
5. Press the OFF button on the HVAC controls.
6. Turn the ignition switch to OFF.

For vehicles repaired under warranty, use: