Grand AM L4-151 2.5L (1986)
Vacuum Reservoir HVAC: All Technical Service Bulletins
HVAC Vacuum Reservoir - Whistle/Moan/Squawk Noise
Number
87-1-9
Date
7/87
Subject:
HVAC VACUUM RESERVOIR NOISE
1986-87 GRAND AM MODELS
Grand Am vehicles built prior to VIN HC814125 may exhibit a noise condition similar to a steering stop or bushing squawk. This noise may be
deceptive in that it can be quite loud and appear to be coming from the dash panel area of the car. The noise is actually the check valve and diaphragm
inside the HVAC vacuum tank located on the right end of the HVAC case in the passenger compartment.
To diagnose the condition:
With the engine running, operate the A/C control through its modes and listen for the noise. If the noise is present,
then disconnect the vacuum source from the vacuum tank. The reservoir should hold vacuum for at least one mode
change. If the reservoir leaks down or it is quiet when mode is changed, then replace the vacuum tank assembly.
The noise may be described as a whistle, a moan, a squawk, a hiss, a vacuum leak or a squeak. The correction is to replace the vacuum tank assembly
with a service replacement part, 10000669, from GMSPO.