Fleetwood FWD V8-252 4.1L (1986)
Compressor Clutch: All Technical Service Bulletins
A/C Compressor - Buzz/Growl/Whine/Moaning Noises
Bulletin No. T
87-1
File in Group
1
Number
28
Corp. Ref. No.
611401
Date
Sept. '86
SUBJECT:
AIR CONDITIONING COMPRESSOR NOISE
MODELS AFFECTED: 1985-86 DE VILLES AND FLEETWOODS EQUIPPED WITH HT4100 ENGINE
This bulletin supersedes bulletins T-84-102A and T-85-100 which should both be destroyed.
Some 1985-1986 FWD De Villes and Fleetwoods may experience a rattle, buzz, growl, whine or moaning noise at certain engine speeds with the air
conditioning (A/C) compressor engaged. This may be caused by vibration of the A/C compressor clutch driver, A/C hoses and/or lines or A/C
compressor pumping pulses. These pressure pulses are transmitted through the A/C compressor hose assembly, condenser, evaporator and accumulator
assemblies. Compressor pulsation noise is more pronounced when operating at maximum cooling demand (high ambient temperatures and humidity).
The following procedure should be followed to properly diagnose and correct these conditions.
DIAGNOSIS
1.
Start car. Set Electronic Climate Control (ECC) to 60~F AUTO mode, LO fan. Allow car to warm up by idling 3-4 minutes.
2.
Enter ECM diagnostic parameter P.1.1 (engine RPM) as described in the Service Information Manual.
3.
With the transaxle in "Park", note the intensity and type of noise(s) when the compressor is engaged at the following engine speeds:
A.
1730 RPM
B.
1650 RPM
C.
1500 RPM
D.
1100 RPM
E.
950 RPM
4.
Set the ECC to 60~F ECON mode, LO fan to disengage the compressor. Again note the intensity and type of noise(s) at the listed engine speeds. If
the noise level does NOT decrease when the A/C compressor is off (ECON mode), then the noise is NOT A/C related and the following
procedures are not applicable.
Figure 1 - A/C Clutch
