C 1500 Truck 2WD V6-262 4.3L VIN Z (1992)
Blower Motor: All Technical Service Bulletins
A/C - Whistling Noise With Blower Fan Turned ON
GMC NUMBER:
92-1B-112
GROUP:
1B Air Conditioning
DATE:
July 1992
CORPORATE
NUMBER:
261205
SUBJECT:
WHISTLING NOISE WITH BLOWER FAN TURNED ON
MODELS:
1992 C/K AND TOPKICK/KODIAK TRUCKS
Some 1992 C/K and Topkick/Kodiak 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.
