LACK OF HEAT OR TEMP. VARIES SIDE TO SIDE. Buick Park Avenue 1992

THIS IS A MONTHLY SERVICE NEWSLETTER ARTICLE. THIS IS NOT INTENDED TO BE A PUBLISHED BULETIN

SUBJECT: LACK OF HEAT OR TEMPERATURE VARIATION SIDE TO SIDE (POSSIBLE HEATER CORE CONCERN)

MODELS: 1991-96 BUICK PARK AVENUE/ULTRA 1992-98 BUICK LESABRE

CONDITION:

HVAC SYSTEM EXHIBITS CONDITION OF POOR HEAT, OR A TEMPERATURE VARIATION BETWEEN THE PASSENGER AND DRIVER SIDE OUTLETS. THE OUTLET TEMPERATURE MAY INCREASE IF PUT INTO ECON MODE (A/C COMPRESSOR OFF).

CAUSE:

POSSIBLE HEATER CORE CONCERN. IF THE LOWER PORTION OF THE HEATER CORE IS RESTRICTED WITH SEDIMENT, THE DRIVER SIDE WILL BLOW COLD WHILE THE PASSENGER SIDE WILL BLOW HOT.

IF AIR IS PRESENT FROM LOW COOLANT, THE AIR WILL STAY IN THE TOP OF THE CORE. THIS WILL CAUSE THE PASSENGER SIDE TO BLOW COLD AND THE DRIVER SIDE TO BLOW HOT. IN EITHER CASE, THE CAPACITY OF THE HEATER CORE HAS BEEN COMPROMISED. THE CORE CAN EASILY OVERCOME THE COOL AIR FROM THE EVAPORATOR; FOR EXAMPLE- THE CAR PRODUCES HEAT IN SUB-ZERO TEMPERATURES. THERE WILL ALSO BE A TEMPERATURE DIFFERENCE BETWEEN THE INLET AND OUTLET HOSES SINCE THE OPERATIONAL HALF OF THE CORE IS STILL TRANSFERRING HEAT, BUT IT IS NOT ENOUGH TO HEAT THE CAR.

CORRECTION:

PRESSURE TEST THE RADIATOR CAP AND COOLING SYSTEM. IF IT TAKES MORE THAN 4-5 PUMPS TO BUILD PRESSURE, THERE IS AIR IN THE SYSTEM. RAISE THE FRONT OF THE CAR WHILE RUNNING TO PURGE THE AIR OUT. IF THE CONDITION RETURNS, CHECK THE SYSTEM FOR HYDROCARBONS WHICH MAY INDICATE AN EARLY HEAD GASKET FAILURE. IF AIR IS NOT PRESENT, BACKFLUSH COOLING SYSTEM THEN REPLACE HEATER CORE. IF THERE IS A LARGE AMOUNT OF SCALING AND SEDIMENT, IT IS POSSIBLE TO RESTRICT THE NEW HEATER CORE RATHER QUICKLY. IT MAY BE NECESSARY TO INSTALL A WATER FILTER ON THE INLET LINE TO THE CORE. THIS FILTER IS THE SIZE OF A 5.7L OIL FILTER, SO FINDING A SUITABLE MOUNTING LOCATION MAY NOT BE POSSIBLE. IT CAN BE TEMPORARILY MOUNTED THEN REMOVED AFTER SOME RUN TIME TO ENSURE SEDIMENT HAS BEEN REMOVED FROM THE SYSTEM.

PARTS INFORMATION:

FILTER: WF-100 P/N 6439692 REMOTE ADAPTER: P/N 25010098

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.