INFO. ON SERVICE ISSUES FOR VEHICLES WITH R12 OR R134A. GMC Truck GMC MD Bus Chassis (B Model) 1996

SUBJECT: INFORMATION ON SERVICE ISSUES FOR VEHICLES WITH R12 OR R134A AIR CONDITIONING SYSTEMS

MODELS: 1988-96 PASSENGER CARS AND TRUCKS

R12 SERVICE RECOMMENDATION

AS YOU KNOW, PRODUCTION OF R12 REFRIGERANT CEASED ON DECEMBER 31, 1995. ALTHOUGH R12 WILL NO LONGER BE MANUFACTURED, THERE IS A RESERVE SUPPLY OF R12 AVAILABLE. THIS RESERVE, ALONG WITH STRICT A/C REPAIR SERVICE ADHERENCE TO PROPER REFRIGERANT RECYCLING PROCEDURES, SHOULD ASSURE CONTINUED AVAILABILITY TO MEET CONSUMERS' NEEDS.

R12 CAN AND SHOULD CONTINUE TO BE USED TO SERVICE VEHICLES BUILT WITH R12 A/C SYSTEMS AS LONG AS IT IS AVAILABLE. IF R12 IS NO LONGER AVAILABLE OR AFFORDABLE, A SYSTEM RETROFIT UTILIZING R134A IS RECOMMENDED. R134A IS THE ONLY SUBSTITUTE REFRIGERANT RECOMMENDED BY GM FOR USE IN GM VEHICLE A/C SYSTEMS, AND THEN ONLY AFTER FOLLOWING THE PROPER RETROFIT PROCEDURES FOR THE SPECIFIC MODEL. ALL NEW VEHICLE MANUFACTURERS HAVE CHOSEN R134A FOR RETROFIT. ONE OF THE KEY REASONS IS TO PROTECT BOTH THE SERVICE INDUSTRY AND CONSUMERS FROM THE HIGH COSTS THAT WOULD RESULT FROM PURCHASING EQUIPMENT NECESSARY TO SERVICE MULTIPLE REFRIGERANTS. THIS POSITION ALSO REDUCES THE THREAT OF RECYCLED REFRIGERANT CONTAMINATION.

GM CURRENTLY OFFERS A SIMPLE, LOW COST R12 TO R134A RETROFIT ON MANY OF ITS LATE MODEL, FRONT WHEEL DRIVE PASSENGER CARS. DEALERS SHOULD DISCUSS THIS CAPABILITY WITH OWNERS OF THESE SPECIFIC MODELS, LISTED IN RETROFIT CORPORATE BULLETIN #43-12-07D, WHENEVER A REPAIR TO THE A/C REFRIGERANT SYSTEM IS REQUIRED. EARLY RETROFIT OF THESE SPECIFIC MODELS WILL AID IN PROLONGING AVAILABILITY OF THE R12 SUPPLY AND PROVIDE DEALER SERVICE TECHNICIANS THE OPPORTUNITY TO BECOME MORE FAMILIAR WITH THE PROPER PROCEDURES FOR PERFORMING A RETROFIT.

REMEMBER - R12 AND R134A REFRIGERANT ARE NOT INTERCHANGEABLE! THEY CANNOT BE MIXED TOGETHER. IN FACT, DESPITE THE CLAIMS OF SOME REFRIGERANT MANUFACTURERS, NO PROPOSED R12 REFRIGERANT SUBSTITUTE CAN BE ADDED TO, MIXED WITH OR USED TO "TOP OFF" AN R12 SYSTEM. UNDER PROVISIONS OF LAW COVERING THE SERVICE OF REFRIGERANTS, MIXING DISSIMILAR REFRIGERANT PRODUCTS DURING SERVICE IS PROHIBITED.

TO SUMMARIZE GM R12 SERVICE POLICY:

1. SERVICE R12 VEHICLES WITH GOOD QUALITY NEW OR RECYCLED R12 AS LONG AS IT IS AVAILABLE.

2. PURCHASE R12 FROM A RELIABLE SUPPLIER. GMSPO HAS A SUPPLY OF HIGH QUALITY R12 AVAILABLE. DEALERS ARE REQUESTED TO USE ONLY R12 SUPPLIED BY GMSPO FOR WARRANTY REPAIRS. THIS HIGH QUALITY REFRIGERANT WILL INSURE SYSTEM PERFORMANCE AND AVOID THE POSSIBILITY OF INTRODUCING CONTAMINATED MATERIAL INTO THE CUSTOMER'S A/C SYSTEM.

3. CAREFULLY TEST RECOVERED R12 USING THE PUREGUARD MONITOR. ON RECOVERY EQUIPMENT NOT PROTECTED BY THE PUREGUARD, ALWAYS TEST THE RECOVERY CYLINDER PRIOR TO RECHARGING A VEHICLE A/C SYSTEM.

4. DISCUSS THE R12 TO R134A RETROFIT OPTION WITH OWNERS OF GM VEHICLES LISTED IN RETROFIT CORPORATE BULLETIN #43-12-07D. PROVIDE OWNER WITH A COPY OF THE PAMPHLET "CONVERTING YOUR AUTO AIR CONDITIONING SYSTEM TO USE THE NEW REFRIGERANT".

5. BECOME FAMILIAR WITH RETROFIT PROCEDURES AND EXERCISE CARE IN THE HANDLING OF DISSIMILAR REFRIGERANTS TO PREVENT CONTAMINATION.

R134A SERVICE RECOMMENDATIONS

WHEN SERVICING A PREVIOUSLY RETROFITTED VEHICLE, THERE IS CONCERN THAT IF ALL OF THE R12 IS NOT COMPLETELY REMOVED PRIOR TO THE RETROFIT PROCEDURE, IT COULD CONTAMINATE YOUR R134A EQUIPMENT AND RECOVERY TANK WHEN A SUBSEQUENT A/C REPAIR IS PERFORMED. ALTHOUGH THE NUMBER OF RETROFITS BEING PERFORMED TODAY IS MINIMAL, THE VOLUME WILL INCREASE AS R12 PRICES RISE.

GM SERVICE TECHNOLOGY GROUP IS IN THE PROCESS OF FIELD TESTING A NEW R134A REFRIGERANT PURITY TESTER SIMILAR TO THE PUREGUARD R12 REFRIGERANT TESTER YOU NOW USE. THIS NEW TOOL WILL MOUNT TO YOUR ACR4 R134A RECOVERY RECYCLE AND RECHARGE CART AND SAMPLE ALL R134A REFRIGERANT PRIOR TO RECOVERY. IT IS EXPECTED THAT TESTING OF THIS TOOL WILL BE COMPLETED THIS YEAR.

THIS NEW TOOL, THE PUREGUARD 2, WILL ALSO TEST VEHICLES AND YOUR RECYCLE TANK FOR AIR CONTAMINATION, WHICH IS THREATENING A/C SYSTEM PERFORMANCE. HIGH LEVELS OF AIR HAVE BEEN FOUND IN THE RECOVERY TANKS ON A NUMBER OF R12 AND R134A RECOVERY CARTS. AIR CONTAMINATION IS CAUSED BY IMPROPER RECOVERY PROCEDURES AND SHORT-CUTTING REFRIGERANT RECYCLING TIMES. USE THE FOLLOWING PROCEDURE FOR TESTING AND CORRECTING AIR CONTAMINATION IN YOUR A/C SERVICE EQUIPMENT.

1. MAKE CERTAIN THAT THE ACR4 EQUIPMENT HAS NOT BEEN USED FOR AT LEAST 12 HOURS. IT IS RECOMMENDED THAT THE EQUIPMENT BE LEFT IN AN AREA WHERE THE TEMPERATURE WILL REMAIN CONSTANT OVERNIGHT TO ALLOW THE TEMPERATURE OF THE REFRIGERANT IN THE TANK TO STABILIZE.

2. RECORD THE SURROUNDING AIR TEMPERATURE NEXT TO THE ACR4 REFRIGERANT TANK.

IMPORTANT: A MAJOR ASSUMPTION IS THAT THE AMBIENT AIR TEMPERATURE NEXT TO THE TANK REPRESENTS THE REFRIGERANT TEMPERATURE IN THE TANK. FAILURE TO TAKE CARE IN MEASURING THE TEMPERATURE COULD RESULT IN UNNECESSARY WORK.

3. CLOSE BOTH LIQUID (BLUE) AND VAPOR (RED) VALVES ON THE ACR4 TANK.

4. DISCONNECT LOW SIDE (BLUE) SERVICE HOSE FROM THE BACK OF THE ACR4.

5. SLOWLY DISCONNECT THE TANK VAPOR HOSE (RED) FROM THE BACK OF THE ACR4 AND CONNECT IT TO THE LOW SIDE SERVICE PORT.

6. OPEN THE VAPOR (RED) VALVE ON THE TANK AND RECORD THE TANK PRESSURE ON THE LOW SIDE GAGE.

7. RESTORE HOSES TO THE ORIGINAL POSITION.

8. REFERRING TO THE TABLE BELOW, FIND THE AMBIENT TEMPERATURE MEASURED IN STEP 2. COMPARE THE PRESSURE READING FROM STEP 6 TO THE "MAXIMUM ALLOWABLE PRESSURE". IF THE PRESSURE READING FROM STEP 6 IS LESS THAN THE "MAXIMUM ALLOWABLE PRESSURE", NO FURTHER ACTION IS NECESSARY.

IMPORTANT: THE CLOSER THE TANK PRESSURE IS TO THE DESIRED TANK PRESSURE, THE BETTER THE A/C SYSTEM WILL PERFORM.

9. IF THE PRESSURE READING FROM STEP 6 EXCEEDS THE MAXIMUM ALLOWABLE PRESSURE FROM THE TABLE, OPEN BOTH TANK VALVES AND OPERATE THE ACR4 THROUGH 4 OR 5 EVACUATION CYCLES. THIS WILL ACTIVATE THE AUTOMATIC AIR PURGE TO LOWER THE TANK PRESSURE.

IMPORTANT: STATION SHOULD NOT BE CONNECTED TO VEHICLE.

10. REPEAT THE TANK PRESSURE CHECKING PROCEDURE THE NEXT DAY TO DETERMINE IF THE PRESSURE HAS BEEN REDUCED TO ACCEPTABLE LEVELS. IF THE TANK PRESSURE HAS BEEN REDUCED BUT IS NOT ACCEPTABLE, CYCLE WITH ACR4 THROUGH MORE EVACUATION CYCLES AND RECHECK THE NEXT DAY. CONTINUE PROCESS UNTIL ACCEPTABLE PRESSURE IS OBTAINED. IF THE TANK PRESSURE IS NOT REDUCED THROUGH THE EVACUATION CYCLING, THEN KENT-MOORE SHOULD BE CONTACTED AT 1-800-345-2233.

AMBIENT DESIRED TANK MAXIMUM ALLOWABLE TEMPERATURE PRESSURE PRESSURE =========== ============ =================

15.5 DEGREES CELSIUS 393 KPA (57 PSI) 476 KPA (69 PSI) (60 DEGREES FAHRENHEIT)

18.3 DEGREES CELSIUS 441 KPA (64 PSI) 531 KPA (77 PSI) (65 DEGREES FAHRENHEIT)

21.1 DEGREES CELSIUS 490 KPA (71 PSI) 593 KPA (86 PSI) (70 DEGREES FAHRENHEIT)

23.8 DEGREES CELSIUS 538 KPA (78 PSI) 662 KPA (96 PSI) (75 DEGREES FAHRENHEIT)

26.6 DEGREES CELSIUS 593 KPA (86 PSI) 724 KPA (105 PSI) (80 DEGREES FAHRENHEIT)

29.4 DEGREES CELSIUS 655 KPA (95 PSI) 800 KPA (116 PSI) (85 DEGREES FAHRENHEIT)

32.2 DEGREES CELSIUS 717 KPA (104 PSI) 876 KPA (127 PSI) (90 DEGREES FAHRENHEIT)

35 DEGREES CELSIUS 786 KPA (114 PSI) 958 KPA (139 PSI) (95 DEGREES FAHRENHEIT)

37.7 DEGREES CELSIUS 855 KPA (124 PSI) 1048 KPA (152 PSI) (100 DEGREES FAHRENHEIT)

FIGURES: 00 ATTACHMENTS: 00

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.