For 1990-2009 cars

# SMU - SECTION 1C - ADDITIONAL INFORMATION FOR OUTSIDE TEMP.

#### SUBJECT: SERVICE MANUAL UPDATE - SECTION 1C - ADDITIONAL INFORMATION FOR OUTSIDE TEMPERATURE SENSOR MEMORY FEATURE

#### MODELS: 1995 BUICK LESABRE, PARK AVENUE 1995 OLDSMOBILE EIGHTY EIGHT, NINETY EIGHT 1995 PONTIAC BONNEVILLE

THE FOLLOWING INFORMATION CONCERNING THE OUTSIDE TEMPERATURE SENSOR SHOULD BE ADDED TO SECTION 1C-8, "AMBIENT TEMPERATURE SENSOR", IN THE SERVICE MANUAL.

DURING PERIODS OF CITY TRAFFIC AND IDLE CONDITIONS, ENGINE HEAT CAN SURROUND THE AREA OF THE OUTSIDE TEMPERATURE SENSOR AND CAUSE TEMPERATURE READINGS THAT ARE HIGHER THAN THE ACTUAL OUTSIDE AIR TEMPERATURE. THE PROGRAMMER IS DESIGNED TO MINIMIZE UNWANTED TEMPERATURE VARIATIONS.

A TEMPERATURE MEMORY FEATURE IS USED IN THE HVAC PROGRAMMER OUTSIDE TEMPERATURE PROGRAMMING TO HELP PROVIDE GREATER ACCURACY UNDER ENGINE RESTART CONDITIONS. IF ENGINE COOLANT TEMPERATURE IS LESS THAN 10 DEGREES CELSIUS (50 DEGREES FAHRENHEIT) ABOVE THE OUTSIDE TEMPERATURE SENSOR READING, THE ACTUAL SENSED OUTSIDE TEMPERATURE IS DISPLAYED. HOWEVER, IF ENGINE COOLANT IS GREATER THAN 10 DEGREES CELSIUS (50 DEGREES FAHRENHEIT) ABOVE THE SENSOR READING, MEMORIZED OUTSIDE TEMPERATURE IS DISPLAYED. THIS IS THE DISPLAYED TEMPERATURE SENSED WHEN THE ENGINE WAS PREVIOUSLY OPERATING.

AT VEHICLE SPEEDS GREATER THAN 32KM (20MPH), THE OUTSIDE TEMPERATURE DISPLAY MAY BE ALLOWED TO INCREASE, BUT ONLY AFTER A BUILT-IN 80 SECOND TIME DELAY WHICH ALLOWS FOR OUTSIDE AIR TO COOL THE SENSOR. THE 80 SECOND TIME DELAY STARTS WHEN VEHICLE SPEED REACHES OR MAINTAINS AT LEAST 32KM (20 MPH). IF THE SENSOR READING IS EVER LESS THAN THE DISPLAYED VALUE OR IF THE VEHICLE SPEED IS 72KM (45MPH) OR GREATER, THERE IS NO DELAY AND OUTSIDE TEMPERATURE CHANGES ARE DISPLAYED AS RAPIDLY AS POSSIBLE. IF THE SENSOR FAILS, A DEFAULT VALUE OF 10 DEGREES CELSIUS (50 DEGREES FAHRENHEIT) WILL BE USED BY THE PROGRAMMER.

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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.

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