WIND WHISTLE IN CAB WITH HEATER BLOWER ON HIGH

VEHICLES AFFECTED: 1983-85 C/K Trucks With Silverado/Sierra Classic Trim ----------------------------------------

Some C/K Silverado/Sierra Classic Trucks may exhibit a wind whistling noise in the area of the vent window or the side door glass lower seal when the HVAC blower is on 'high'.

This condition is the result of a restriction in air flow from the cab interior to the outside environment. The following procedure will improve the air flow and eliminate the whistle.

1. Remove lower door trim panel, exposing louvers at the bottom of the door.

2. Unscrew the two screws retaining the air valve assembly behind door louvers. Let the valve assembly drop to the bottom of the door.

3. Use a die grinder with a cut-off wheel to cut the louvers out of the door. Remove any material falling inside the door.

4. Smooth any rough edges with a file.

5. Paint exposed metal edges to prevent corrosion.

6. Reinstall air valve assembly.

Note: It is imperative that the air valve assembly is not damaged and that it is reinstalled correctly. Failure to do so could result in cold air and/or exhaust fume entry into the cab.

7. Reinstall lower door trim panel.

The time required to perform the above service procedure on two doors is 0.4 hours.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.