Test Description

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The numbers below refer to the step numbers on the diagnostic table.

2. This step ensures that the primary HVAC system is functioning properly.
5. If the condition does not occur when a heating request has been made then you must bypass the A/C compressor and cooling system diagnostic information.
7. This step ensures that the rear auxiliary HVAC control module is able to move the auxiliary air temperature actuator.
8. This step ensures that the front auxiliary HVAC control assembly is able to move the auxiliary air temperature actuator.
9. There is 2 ignition 3 voltage circuits for the rear HVAC control assembly. The circuit that needs to be tested is the circuit that supplies ignition 3 voltage to the auxiliary HVAC control processor. If this circuit is open the auxiliary mode and air temperature actuators will not move with in there full range of motion.
12. There is 2 ignition 3 voltage circuits for the rear HVAC control assembly. The circuit that needs to be tested is wired between the left I/P fuse block and the rear HVAC control assembly.
14. The circuit that is to be tested is wired between the rear auxiliary HVAC control assembly and the auxiliary HVAC control processor. The circuit is the position signal from the rear auxiliary HVAC control assembly for the auxiliary air temperature actuator. The circuit only provides a reference when the front auxiliary HVAC control assembly is in the AUX position.
17. The circuit that is to be tested is wired between the front auxiliary HVAC control assembly and the auxiliary HVAC control processor. The circuit is the position signal from the rear auxiliary HVAC control assembly for the auxiliary air temperature actuator. The circuit only provides a reference when the front auxiliary HVAC control assembly is in any other position than AUX position.
22. This step checks the output of the auxiliary HVAC control processor to the auxiliary air temperature actuator.

Fig 1: Diagnosis Procedure Too Cold In Vehicle - Auxiliary - With Heat And A/C (Step 1 To 5)
Courtesy of GENERAL MOTORS CORP.

Fig 2: Diagnosis Procedure Too Cold In Vehicle - Auxiliary - With Heat And A/C (Step 6 To 13)
Courtesy of GENERAL MOTORS CORP.

Fig 3: Diagnosis Procedure Too Cold In Vehicle - Auxiliary - With Heat And A/C (Step 14 To 21)
Courtesy of GENERAL MOTORS CORP.

Fig 4: Diagnosis Procedure Too Cold In Vehicle - Auxiliary - With Heat And A/C (Step 22 To 32)
Courtesy of GENERAL MOTORS CORP.