SOME OWNERS MAY COMMENT THEY DO NOT PERCEIVE A SHIFT IN AIRFLOW DIRECTION AFTER SWITCHING FROM DEFROST MODE TO BLEND/DEFOG MODE. (CHEVROLET REFERS TO THIS MODE AS "BLEND". BUICK AND CADILLAC REFER TO THIS MODE AS "DEFOG".) THE AIRFLOW WOULD CONTINUE TO EXIT FROM THE DEFROST OUTLET AFTER CHANGING MODES. AIRFLOW IN BLEND/DEFOG MODE SHOULD BE APPROXIMATELY 45 PERCENT FROM THE DEFROST OUTLET AND 45 PERCENT FROM THE HEATER OUTLET WITH THE REST EXITING THE SIDE WINDOW DEFOG OUTLETS. AIR FLOW IN DEFROST SHOULD BE PRIMARILY FROM THE DEFROST OUTLET.
THE HEATER/DEFROST VALVE RETURN SPRING IS MISSING OR DISLODGED.
1. USING HIGH BLOWER MOTOR SPEED, VERIFY AIRFLOW AFTER SHIFTING FROM DEFROST TO BLEND/DEFOG. (THIS CONDITION WILL NOT BE PRESENT AFTER SHIFTING FROM HEATER MODE TO BLEND/DEFROST.)
2. LOCATE THE HEATER/DEFROSTER VALVE AND VERIFY THAT THE SPRING IS PRESENT AND/OR IN THE CORRECT POSITION. (SEE FIGURE 1).
3. IF THE SPRING IS PRESENT, BUT NOT ATTACHED TO THE HEATER/ DEFROSTER VALVE, REINSTALL PER FIGURE 1. IF IT IS NOT PRESENT, REPLACE WITH P/N 3094308.
PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.
FOR VEHICLES REPAIRED UNDER WARRANTY, USE: LABOR OPERATION: T-3418 LABOR OPERATION TIME: 0.2 HR.
FIGURES: 1
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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