A/C CONTROL HEAD FLASHES/ ERRATIC OPER. OF A/C CONTROLS. GMC Truck GMC MD Conventional (C Model) 1990

SUBJECT: A/C CONTROL HEAD FLASHES OR ERRATIC OPERATION OF A/C CONTROLS (POLISH TERMINALS)

MODELS: 1988-94 CHEVROLET AND GMC TRUCK C/K MODELS 1990-94 CHEVROLET AND GMC TRUCK TOPKICK/KODIAK MODELS WITH C60 OR C69 AIR CONDITIONING

CONDITION:

A/C CONTROL HEAD FLASHES, PERFORMS ERRATICALLY OR MALFUNCTIONS.

CAUSE:

LIGHT SURFACE CORROSION ON THE CONTROL HEAD TERMINALS.

CORRECTION:

REMOVE THE A/C CONTROL HEAD AND WHILE HOLDING THE UNIT WITH THE TERMINAL CAVITY DOWN (TOWARD THE FLOOR) SO NO PARTICLES WILL FALL INSIDE ON THE CIRCUIT BOARDS, POLISH THE TERMINALS ON BOTH SIDES OF THE CAVITY WITH A LEAD PENCIL PINK ERASER. DO NOT USE AN INK ERASER OR OTHER ABRASIVE SUCH AS A SMALL WIRE BRUSH OR SANDPAPER, ETC. DOING SO WILL REMOVE THE TERMINAL COATING AND DEGRADE THE CONTACT SURFACE.

**PERFORMING THIS PROCEDURE, IN MANY CASES, WILL MAKE REPLACING THE CONTROL HEAD UNNECESSARY.** USING THIS PROCEDURE IN CONJUNCTION WITH THE A/C CIRCUIT DIAGNOSIS FOUND IN THE ELECTRICAL DIAGNOSIS MANUAL AND ESPECIALLY BEFORE REPLACING A CONTROL HEAD FOR ANY REASON IS RECOMMENDED.

AFTER POLISHING THE CONTROL HEAD TERMINALS, BUT BEFORE RECONNECTING, CHECK FOR PROPER TERMINAL CONTACT AS DESCRIBED IN THE APPLICABLE ELECTRICAL DIAGNOSIS MANUAL. IF CONTACT IS GOOD, APPLY DIELECTRIC GREASE (P/N 12345579) TO THE HARNESS CONNECTOR TERMINALS. PLEASE DO NOT APPLY GREASE TO THE CONTROL HEAD.

SERVICE PARTS INFORMATION:

P/N DESCRIPTION QTY 12345579 DIELECTRIC GREASE FROM TUBE AS NEEDED

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OP DESCRIPTION LABOR TIME D0362 A/C CONTROL ASSEMBLY USE PUBLISHED REPLACE LABOR OPERATION TIME

FIGURES: 0

CAPTIONS:

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.