For 1990-2009 cars

# A/C COMPRESSOR MOAN NOISE (REPL. A/C COMPRESSOR CLUTCH)

#### SUBJECT: A/C COMPRESSOR MOAN NOISE (REPLACE A/C COMPRESSOR CLUTCH DRIVER)

#### MODELS: 1992-1993 CADILLAC DE VILLES 1992-1993 CADILLAC FLEETWOODS (FWD) 1992-1993 CADILLAC SIXTY SPECIALS

THIS BULLETIN IS BEING ISSUED TO REVISE AND SUPPLEMENT THE INFORMATION CONTAINED IN SERVICE BULLETIN T-93-80 (CORPORATE BULLETIN NUMBER 311401) ONLY FOR USE WHEN SERVICING 1992-1993 DEVILLES, FLEETWOODS (FWD), AND SIXTY SPECIALS.

#### CONDITION:

SOME VEHICLES MAY EXHIBIT A WHINE OR MOAN NOISE WHICH IS EVIDENT ONLY AT CERTAIN ENGINE SPEED RANGES (1400-2100 RPM) WITH THE A/C COMPRESSOR ENGAGED. THIS COMPRESSOR MOAN NOISE IS MORE PRONOUNCED WHEN OPERATING AT MAXIMUM COOLING DEMAND (HIGH AMBIENT TEMPERATURE AND HUMIDITY).

#### CAUSE:

THIS MOAN NOISE MAY BE CAUSED BY TORSIONAL SHAFT NOISE OR PUMPING PULSES WHICH ARE TRANSMITTED TO THE VEHICLE VIA THE COMPRESSOR MOUNTING OR HOSE INTERFACES.

#### CORRECTION:

#### IMPORTANT: A/C COMPRESSOR NOISE MAY BE CREATED, TRANSMITTED, OR AMPLIFIED BY THE FOLLOWING CONDITIONS: A HOSE, LINE, OR COMPONENT WHICH IS GROUNDED TO THE VEHICLE STRUCTURE OR IMPROPERLY SECURED/TORQUED BRACKETS OR BRACES CAN REACT WITH THE OPERATION OF THE COMPRESSOR CAUSING A NOISE PATH THROUGH THE BODY STRUCTURE OF THE VEHICLE. TO ASSURE A SUCCESSFUL CORRECTION IT IS NECESSARY TO CONFIRM PROPER POSITIONING OF HOSES, LINES, AND COMPONENTS AND PROPER TORQUES OF ALL BRACES AND BRACKETS IN THE SYSTEM AS WELL AS THE EXHAUST (MUSTACHE) BRACKET. PLACEMENT OF A WASHER UNDER THE HEAD OF THE FRONT AND REAR COMPRESSOR MOUNTING BRACKET TO BLOCK MOUNTING FASTENERS PRIOR TO RETORQUING WILL ASSURE THAT THE FASTENER HAS NOT "BOTTOMED OUT" IN THE MOUNTING HOLE. IN SOME CASES, IT MAY BE NECESSARY TO ISOLATE A COMPONENT BY WRAPPING IT IN FOAM OR RUBBER TO DISRUPT THE NOISE PATH.

IF THE CONDITION STILL EXISTS AFTER CAREFUL EXAMINATION OF THE SYSTEM FOR NOISE PATHS, REPAIR BY REPLACING THE A/C COMPRESSOR CLUTCH DRIVER WITH A DAMPED SERVICE CLUTCH DRIVER AND NEW "SOFT" SHAFT KEY ASSEMBLY KIT CONTAINED IN P/N 2724583.

THIS PROCEDURE CAN BE DONE ON THE VEHICLE AND WITHOUT THE NEED FOR REFRIGERANT RECOVERY AND RECHARGE. DETAIL DESCRIPTION AND ILLUSTRATIONS FOR REMOVING AND REPLACING THIS CLUTCH DRIVER MAY BE FOUND IN SECTION 1D2 "COMPRESSOR CLUTCH PLATE AND HUB ASSEMBLY" OF THE SERVICE INFORMATION MANUAL.

1. LOOSEN RIGHT FRONT ENGINE MOUNTING CRADLE BOLT 8-10 TURNS.

2. REMOVE WHEEL WELL SPLASH SHIELD.

3. REMOVE SHAFT NUT USING SHAFT NUT SOCKET J-33022.

4. REMOVE CLUTCH PLATE AND HUB ASSEMBLY USING CLUTCH PLATE REMOVER-INSTALLER J-33013-B.

5. REMOVE SHAFT KEY AND DISCARD.

6. INSTALL NEW SHAFT KEY INTO THE HUB KEY GROOVE. ALLOW THE KEY TO PROJECT APPROXIMATELY 3.2 MM (1/8") OUT OF THE KEY WAY.

#### IMPORTANT: NEW CLUTCH KEY PROVIDED WITH THE KIT MUST BE USED. USE OF OLD KEY MAY DAMAGE NEW CLUTCH DRIVER.

7. BE SURE FRICTION SURFACE OF THE CLUTCH PLATE AND THE CLUTCH ROTOR ARE CLEAN BEFORE INSTALLING THE CLUTCH PLATE AND HUB ASSEMBLY.

8. ALIGN CLUTCH KEY WAY WITH NEW SHAFT KEY TO SLIDE CLUTCH AND HUB ASSEMBLY ONTO COMPRESSOR SHAFT USING CLUTCH PLATE REMOVER/INSTALLER J-33013-B.

9. SET AIR GAP BETWEEN FRICTIONAL SURFACES OF THE CLUTCH PLATE AND PULLEY ROTOR TO .63 MM (.025").

10. ASSEMBLE AND TIGHTEN SHAFT NUT TO 17 N.M (12 LBS. FT.).

11. REPLACE WHEEL WELL SPLASH SHIELD.

12. TIGHTEN RIGHT FRONT CRADLE BOLT TO TORQUE SPECIFICATION OF 100 N.M (75 LBS. FT.).

#### IMPORTANT: FAILURE TO COMPLETE STEP 13 COULD RESULT IN A SLIPPING CONDITION IN THE NEW CLUTCH.

13. WITH CONTROL HEAD TEMPERATURE SET AT 60, ENGINE RUNNING, ENGAGE THE COMPRESSOR 50 TIMES BY ALTERNATING BETWEEN "ECON" AND "AUTO". THIS OPERATION WILL ENSURE PROPER BREAK IN OF THE CLUTCH DRIVER AND THE PULLEY AND ELIMINATE POSSIBLE CLUTCH SLIPPAGE DURING EXTENDED A/C COMPRESSOR OPERATION.

14. IF THE NOISE CONDITION STILL PERSISTS AFTER EVALUATION, INSTALL REVISED A/C COMPRESSOR HOSE ASSEMBLY (P/N 25624146). FOLLOW REPLACEMENT PROCEDURES FOUND IN SECTION 1B OF THE SERVICE INFORMATION MANUAL.

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

#### WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE: LABOR OPERATIONS T6549 (STEPS 1-13) AT .9 HOUR AND T6762 (STEPS 1-14) AT 2.2 HOURS

FIGURES: 0

GENERAL MOTORS BULLETINS ARE INTENDED FOR USE BY PROFESSIONAL TECHNICIANS, NOT A "DO-IT-YOURSELFER". THEY ARE WRITTEN TO INFORM THOSE TECHNICIANS OF CONDITIONS THAT MAY OCCUR ON SOME VEHICLES, OR TO PROVIDE INFORMATION THAT COULD ASSIST IN THE PROPER SERVICE OF A VEHICLE. PROPERLY TRAINED TECHNICIANS HAVE THE EQUIPMENT, TOOLS, SAFETY INSTRUCTIONS AND KNOW-HOW TO DO A JOB PROPERLY AND SAFELY. IF A CONDITION IS DESCRIBED, DO NOT ASSUME THAT THE BULLETIN APPLIES TO YOUR VEHICLE, OR THAT YOUR VEHICLE WILL HAVE THAT CONDITION. SEE A GENERAL MOTORS DEALER SERVICING YOUR BRAND OF GENERAL MOTORS VEHICLE FOR INFORMATION ON WHETHER YOUR VEHICLE MAY BENEFIT FROM THE INFORMATION.

COPYRIGHT 1993 CADILLAC MOTOR CAR DIVISION, GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.