SMU-SEC. 1C - ELEC. AUTO. AIR COND. - ADD PROC. TO PERFORM. Chevrolet Corvette 1996

SUBJECT: SERVICE MANUAL UPDATE - SECTION 1C - ELECTRONIC AUTOMATIC AIR CONDITIONING - ADDITIONAL PROCEDURE TO PERFORM PRIOR TO REPLACING TEMPERATURE DOOR MOTOR

MODELS: 1996 CHEVROLET CORVETTE

THIS BULLETIN IS BEING ISSUED TO INCLUDE AN ADDITIONAL PROCEDURE THAT IS TO BE PERFORMED PRIOR TO REPLACEMENT OF THE TEMPERATURE DOOR MOTOR. THE FOLLOWING INFORMATION SHOULD BE ADDED TO SECTION 1C OF THE SERVICE MANUAL.

IN SOME CASES, THE TEMPERATURE DOOR MOTOR FOR THE ELECTRONIC AUTOMATIC AIR CONDITIONING SYSTEM MAY BECOME INOPERATIVE. UNDER MOST CIRCUMSTANCES, AN HVAC DIAGNOSTIC TROUBLE CODE (DTC) 01 OR 02 WILL BE SET; HOWEVER, SOME CONDITIONS MAY EXIST WHICH WILL CAUSE THE TEMPERATURE DOOR MOTOR TO BECOME INOPERATIVE BUT NOT SET A TROUBLE CODE. IF THE CONCERN OF AN INOPERATIVE TEMPERATURE DOOR MOTOR EXISTS WITHIN A VEHICLE AND NO DIAGNOSTIC TROUBLE CODES ARE SET, TECHNICIANS ARE INSTRUCTED TO FOLLOW THE DIAGNOSTIC TABLE ON PAGE 1C-7 OF THE SERVICE MANUAL. IF THE TECHNICIAN IS LED TO REPLACEMENT OF THE TEMPERATURE DOOR MOTOR, THEY SHOULD PERFORM THE FOLLOWING STEPS BEFORE ACTUAL REPLACEMENT IS PERFORMED.

1. DISCONNECT BOTH THE TEMPERATURE DOOR MOTOR AND THE HEATER AND A/C PROGRAMMER CONNECTORS.

2. USING A DMM, CHECK CKT'S 733, 605, AND 407 FOR CONTINUITY BETWEEN THE TEMPERATURE DOOR MOTOR AND THE HEATER AND A/C PROGRAMMER CONNECTORS.

3. USING A DMM, CHECK CKT'S 733, 605, AND 407 FOR BEING SHORTED TO GROUND.

4. RECONNECT ONLY THE HEATER AND A/C PROGRAMMER CONNECTOR. TURN THE IGNITION SWITCH TO THE "ON" POSITION. USING A DMM, CHECK FOR A 5 VOLT REFERENCE SIGNAL BEING SENT TO THE TEMPERATURE DOOR MOTOR CONNECTOR FROM THE HEATER AND A/C PROGRAMMER.

5. IF ALL OF THE ABOVE TESTS DO NOT LOCATE A CONCERN, THEN REPLACE THE TEMPERATURE DOOR MOTOR.

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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.