A/C - Whine/Metallic Buzz/Rattle
Bulletin No. T 84-102AFile in Group 1
Number 17
Corp. Ref. No. 805 0434
Date Nov. '85
SUBJECT: AIR CONDITIONING CLUTCH DRIVER NOISE
MODELS AFFECTED: 1985 DE VILLES AND FLEETWOODS EQUIPPED WITH HT4100 ENGINE
This bulletin supersedes Serviceman Bulletin T-84-102, Group 1, which should be destroyed.
A new design "thin" damped A/C clutch driver service kit P/N 3092084 is available. This kit replaces service kit P/N 2724325 and reduces A/C compressor whine, while also eliminating the buzz/metallic A/C induced rattle at 1650 and 1100 RPM.
Some 1985 FWD De Ville and Fleetwood owners may experience a rattle, buzz, growl, whine or moaning noise which is evident only at certain engine speed ranges with the air conditioning (A/C) compressor engaged. This noise may be caused by vibration of the A/C compressor clutch driver, A/C hoses and/or lines and A/C compressor pumping pressure 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.
1. Start car. Set Electronic Climate Control as follows: 60~F AUTO mode, LO fan. Allow car to warm up by idling 3-4 minutes.
2. Enter ECM diagnostics as described on page 1C-16 of the 1985 FWD De Ville and Fleetwood Service Information Manual. Enter E.9.0 ECM data display diagnostic parameter P.1.1 (engine RPM).
3. With the transaxle in "Park", observe and record the level and sound of noises when the compressor is engaged ("Outside Temp" status light is displayed on the CCP) at the following engine speeds:
A. 1730 RPM
B. 1650 RPM
C. 1500 RPM
D. 1100 RPM
E. 950 RPM
4. Set the Electronic Climate Control as follows: 60~F ECON mode, LO fan.
5. With the transaxle in "Park", once again observe and record the level and sound of noises at the above 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.
If a metallic-type rattle, buzz, growl, whine or moaning noise is present, the following procedures should be followed to correct this condition.
1. Perform BCM PROM check and replace as required, per Serviceman Bulletin No. T-85-86, Group 1, Number 23, "Insufficient A/C Cooling at Idle".
2. Replace A/C compressor clutch driver with thin damped service clutch driver kit, P/N 3092084. This kit should be installed using the following procedure.
A. Open hood, remove drive belt from compressor pulley and hoist vehicle.
B. Remove engine splash shield from inside right front wheelhouse by disengaging the four retainers.
C. Remove right front frame bolt plastic dust cover.
D. Loosen frame bolt as required to provide clearance for clutch driver removal/installation.
E. Remove A/C compressor clutch driver dust cover Torx screws and remove cover, if applicable. Discard the dust cover since it cannot be used with the new clutch driver. The new clutch driver has an integral dust cover. Remove clutch driver nut.
F. Remove clutch driver from compressor using tool J-33013-B. Refer to 1985 FrontWheel-Drive De Ville and Fleetwood Service Information Manual, page 1D2-2, for procedure.
G. Thoroughly clean any grease or oil film from clutch face on pulley.
H. Position new clutch driver on compressor shaft. Be sure that the key and keyway are properly aligned. Using tool J-33013-B, install new clutch driver on compressor shaft. Refer to 1985 Front-Wheel-Drive De Ville and Fleetwood Service Information Manual, page 1D2-2, for procedure. When using this procedure, substitute special tool J-25030 (clutch hub holding tool) for tool J-33027. Install clutch driver nut.
I. Install/tighten frame bolt and dust cover which were loosened or removed in steps C and D. Lower vehicle.
J. Reinstall the drive belt on the A/C compressor pulley.
K. With the engine running, cycle the A/C compressor "OFF" and "ON" several times to burnish the clutch surface and ensure proper operation.
For warranty purposes, use Operation Number D4240 at .6 hour.
3. Evaluate noise level per the aforementioned procedure. If the noise level did not decrease, refer to Serviceman Bulletin No. T-85-100, Group 1, Number 24, "Air Conditioning Compressor Growl."