The auxiliary air temperature actuator is a 3-wire bi-directional electric motor. Ignition 3 voltage, ground and control circuits enable the actuator to operate. The control circuit uses a 0-12 volts linear-ramped signal to command the actuator movement. The 0 and 12-volt control values represent the opposite limits of the actuator range of motion. The values in between 0 and 12 volts correspond to the positions between the limits.

When the HVAC control assembly sets a commanded, or targeted, value, the control signal is set to a value between 0-12 volts. The actuator shaft rotates until the commanded position is reached. The module will maintain the control value until a new commanded value is needed.

Inspect the auxiliary air temperature door and the auxiliary air temperature actuator for the following conditions:

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

With Rear Auxiliary Controls

1. Ignition ON, cycle the front auxiliary HVAC control assembly blower switch through the LOW, MED, and HIGH speeds. The blower motor should operate at all speeds.

⇒	If the blower motor is inoperative, refer to Auxiliary Blower Motor Malfunction .

2. Rotate the front auxiliary HVAC control assembly air temperature control from the full COLD position to the full HOT position. The air temperature should follow the commanded states of full HOT to full COLD.

⇒	If the air temperature does not change, refer to Air Temperature Malfunction - Front Auxiliary Control.

3. Front auxiliary HVAC control assembly blower switch in the AUX position, cycle the rear auxiliary HVAC control assembly blower switch through the LOW, MED, and HIGH speeds. The blower motor should operate at all speeds.

⇒	If the blower motor is inoperative, refer to Auxiliary Blower Motor Malfunction .

4. Rotate the rear auxiliary HVAC control assembly air temperature control from the full COLD position to the full HOT position. The air temperature should follow the commanded states of full HOT to full COLD.

⇒	If the air temperature does not change, refer to Air Temperature Malfunction - Rear Auxiliary Control.

Without Rear Auxiliary Controls

1. Ignition ON, cycle the front auxiliary HVAC control assembly blower switch through the LOW, MED, and HIGH speeds. The blower motor should operate at all speeds.

⇒	If the blower motor is inoperative, refer to Auxiliary Blower Motor Malfunction .

2. Rotate the front auxiliary HVAC control assembly air temperature control from the full COLD position to the full HOT position. The air temperature should follow the commanded states of full HOT to full COLD.

⇒	If the air temperature does not change, refer to Air Temperature Malfunction without Rear Auxiliary Control.

Air Temperature Malfunction - Front Auxiliary Control

1. Ignition OFF, disconnect the harness connector at the front auxiliary HVAC control assembly.
2. Ignition ON, verify a test lamp illuminates between the ignition circuit terminal J and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

3. Ignition OFF, connect the harness connector at the front auxiliary HVAC control assembly. Disconnect the harness connector at the auxiliary HVAC control assembly.
4. Ignition ON, test for ignition voltage between the signal circuit terminal A and ground.

⇒	If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the front auxiliary HVAC control assembly.

5. Ignition OFF, connect the harness connector at the auxiliary HVAC control assembly. Disconnect the harness connector at the auxiliary air temperature actuator.
6. Test for less than 5 ohms between the ground circuit terminal 7 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

7. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 10 and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

8. Install a DMM between the control circuit terminal 8 and ground. Command the actuator in each direction. Voltage on the control circuit should change from 0 volts when commanding the actuator in one direction to 12 volts in the other direction.

⇒	If the voltage does not change as specified, replace the auxiliary HVAC control assembly.

9. If all circuits test normal, test or replace the auxiliary air temperature actuator.

Air Temperature Malfunction - Rear Auxiliary Control

1. Ignition OFF, disconnect the harness connector at the rear auxiliary HVAC control assembly.
2. Test for less than 5 ohms between the ground circuit terminal B and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify a test lamp illuminates between the ignition circuit terminal G and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

4. Ignition OFF, connect the harness connector at the front auxiliary HVAC control assembly. Disconnect the harness connector at the auxiliary HVAC control assembly.
5. Ignition ON, test for ignition voltage between the signal circuit terminal C and ground.

⇒	If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the rear auxiliary HVAC control assembly.

6. If all circuits test normal, replace the auxiliary HVAC control assembly.

Air Temperature Malfunction without Rear Auxiliary Control

1. Ignition OFF, disconnect the harness connector at the front auxiliary HVAC control assembly.
2. Ignition ON, verify a test lamp illuminates between the ignition circuit terminal G and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

3. Ignition OFF, connect the harness connector at the front auxiliary HVAC control assembly. Disconnect the harness connector at the auxiliary air temperature actuator.
4. Test for less than 5 ohms between the ground circuit terminal 7 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

5. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 10 and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

6. Install a DMM between the control circuit terminal 8 and ground. Command the actuator in each direction. Voltage on the control circuit should change from 0 volts when commanding the actuator in one direction to 12 volts in the other direction.

⇒	If the voltage does not change as specified, replace the front auxiliary HVAC control assembly.

7. If all circuits test normal, test or replace the auxiliary air temperature actuator.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.