The numbers below refer to the step numbers on the diagnostic table.
The specified values are from the A/C System Performance Test.
The functionality of the auxiliary air temperature drive shaft is questioned.
The functionality of the auxiliary air temperature door control circuit of the auxiliary HVAC control module is questioned.
This step questions the status of the air temperature door control signal communication between the front and auxiliary HVAC control module equipped in the Vehicle Entertainment System.
This step checks for proper auxiliary air temperature actuator drive shaft movement.
The value will vary between 0-255 counts during normal operation. The HVAC control module connector must be connected during this step. This checks for proper operation of the air temperature actuator door control circuit and the HVAC control module.
The value will vary between 0-255 counts during normal operation. The HVAC control module connector must be connected during this step. This checks for proper operation of the air temperature actuator door control circuit and the HVAC control module.
The auxiliary blower motor switch control circuit should not have continuity to ground when front auxiliary blower control switch is in any position except auxiliary control.
The value will vary between 0-255 counts during normal operation. The HVAC control module connector must be connected during this step.
Step | Action | Value(s) | Yes | No | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: Auxiliary air temperature cannot be adjusted from the auxiliary controls or the auxiliary heating is insufficient. This table diagnoses vehicles equipped with the auxiliary HVAC control module. | ||||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||||||
2 | The auxiliary HVAC control module cannot request A/C compressor operation. An A/C request must be generated by the front HVAC control module to provide cooled airflow through the auxiliary system. Does the HVAC control module operate and provide sufficient heating? | -- | Go to Step 3 | |||||||||||
3 |
Does the scan tool display any DTC B0428, B0429, B0434, B3531, B3532, or B3782? | -- | Go to Step 4 | |||||||||||
4 |
Does the auxiliary blower motor operate at all? | -- | Go to Step 5 | |||||||||||
5 | Does the auxiliary blower motor operate in each speed position? | -- | Go to Step 6 | |||||||||||
6 |
Does the A/C compressor operate? | -- | Go to Step 7 | |||||||||||
Perform the A/C System performance test. Refer to Air Conditioning (A/C) System Performance Test . Did you find and correct the condition? | -- | Go to Step 35 | Go to Step 8 | |||||||||||
Does the Auxiliary Too Cold in Vehicle condition happen only with the auxiliary HVAC control module? | -- | Go to Step 11 | Go to Step 9 | |||||||||||
Does the Auxiliary Too Cold in Vehicle condition occur only when using the front HVAC control module? | -- | Go to Step 15 | Go to Step 10 | |||||||||||
Does the Auxiliary Too Cold in Vehicle condition happen with both the front and auxiliary HVAC control modules? | -- | Go to Step 17 | Go to Too Hot in Vehicle | |||||||||||
Does the value measured stay within the specified range with a smooth transition between COLD and HOT? | 0-255 Counts | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 12 | |||||||||||
Does the value measured stay within the specified range with a smooth transition between COLD and HOT? | 0-255 Counts | Go to Step 13 | Go to Step 22 | |||||||||||
13 | Connect a test light between the auxiliary air temperature actuator door control circuit and the ground circuit of the auxiliary air temperature actuator. Does the test light illuminate? | -- | Go to Step 21 | Go to Step 14 | ||||||||||
14 | Connect a test light between the auxiliary air temperature actuator door control circuit and a good ground. Does the test light illuminate? | -- | Go to Step 23 | Go to Step 24 | ||||||||||
Does the value measured stay within the specified range with a smooth transition between COLD and HOT? | 0-255 Counts | Go to Step 16 | Go to Step 26 | |||||||||||
Does the test lamp illuminate? | -- | Go to Step 25 | Go to Step 18 | |||||||||||
17 | Connect a test lamp between the ignition 1 voltage circuit of the front HVAC control module and a good ground . Does the test lamp illuminate? | -- | Go to Step 30 | Go to Step 26 | ||||||||||
Does the value measure within the specified range with a smooth transition between COLD and HOT? | 0-255 Counts | Go to Step 19 | Go to Step 26 | |||||||||||
19 |
Does the test lamp illuminate? | -- | Go to Step 26 | Go to Step 20 | ||||||||||
20 | Connect test lamp between the ignition 3 voltage circuit of the auxiliary blower motor and a good ground. Does the test lamp illuminate? | -- | Go to Step 25 | Go to Step 28 | ||||||||||
21 | Inspect the auxiliary air temperature door and the auxiliary air temperature actuator for the following conditions:
Did you find and correct the condition? | -- | Go to Step 35 | Go to Step 29 | ||||||||||
22 | Test the auxiliary air temperature door control circuit of the auxiliary air temperature actuator from the HVAC control module to the auxiliary air temperature actuator for the following conditions:
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 35 | Go to Step 25 | ||||||||||
23 | Test the ground circuit of the auxiliary air temperature actuator for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 35 | Go to Step 29 | ||||||||||
24 | Test the auxiliary air temperature door control circuit of the auxiliary air temperature actuator from the HVAC control module to the auxiliary HVAC control module for the following conditions:
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 35 | Go to Step 30 | ||||||||||
25 | Test the rear auxiliary blower motor speed control circuit for short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 35 | Go to Step 28 | ||||||||||
26 | Test the auxiliary air temperature common door control circuit between the front HVAC control module and splice 253 for the following conditions:
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 35 | Go to Step 28 | ||||||||||
27 | Test the rear auxiliary blower motor control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 35 | Go to Step 30 | ||||||||||
28 | Test the ignition 3 voltage circuit of the auxiliary blower motor for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 35 | Go to Step 30 | ||||||||||
29 | Inspect for poor connections at the harness connector of the auxiliary air temperature actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 35 | Go to Step 32 | ||||||||||
30 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 35 | Go to Step 33 | ||||||||||
31 | Inspect for poor connections at the harness connector of the auxiliary HVAC control module or vehicle entertainment system (VES). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 35 | Go to Step 34 | ||||||||||
32 | Replace the auxiliary air temperature actuator. Refer to Auxiliary Temperature Valve Actuator Replacement . Did you complete the replacement? | -- | Go to Step 35 | -- | ||||||||||
33 | Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 35 | -- | ||||||||||
34 | Replace the auxiliary HVAC control module part of the VES. If not equipped with a VES, then replace the auxiliary HVAC control module. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 35 | -- | ||||||||||
35 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 |