C 2500 Truck 2WD V8-379 6.2L DSL VIN J FI (1992)
Housing Assembly HVAC: Customer Interest
A/C - Whistling Noise With Blower Fan Turned ON
Number:
92-266-1A
Section:
1A
Date:
AUGUST 1992
Corporate Bulletin No.:
261205
ASE No.:
A7
Subject:
WHISTLING NOISE WITH BLOWER FAN TURNED ON
Model and Year:
1992 C/K TRUCKS
Some 1992 C/K trucks may make a whistling type noise with the blower fan turned on. Noise may occur in all modes or in only one mode often at higher
blower speeds. The cause of the noise is usually an air gap or hole between the module seams.
The noise has often been mistakenly diagnosed as blower motor noise, especially if the gap is located between the scroll cage and the evaporator case.
The noise source can often be verified by applying pressure to various places on the module and scroll case and noting a change in the noise. Running a
hand along the seams can also produce a variation in module noise. True blower motor noise should remain the same when either of these techniques are
used.
Areas of the module that contain unheated air are already sealed but may still cause a noise if the sealer does not fully cover the gap.
