The air temperature actuator is a 5-wire bi-directional electric motor that incorporate a feedback potentiometer. Low reference, 5-volt reference, position signal, and 2 control circuits enable the actuators to operate. The control circuits use either a 0 or 12-volt value to coordinate the actuator movement. When the actuator is at rest, both control circuits have a value of 0 volts. In order to move the actuator, the HVAC control module grounds one of the control circuits while providing the other with 12 volts. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction. When the actuator shaft rotates, the potentiometer's adjustable contact changes the door position signal between 0-5 volts.

Air Conditioning (A/C) System Performance Test

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

Schematic Reference

HVAC Schematics

Connector End View Reference

HVAC Connector End Views

Description and Operation

Electrical Information Reference

Scan Tool Reference

Ignition ON, operate the applicable actuator using the HVAC controls. The applicable scan tool parameter should transition from 7 counts to 250 counts.

1. Ignition OFF, disconnect the air temperature actuator harness connector at the air temperature actuator.
2. Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit terminal 1 and ground.

⇒	If greater than 1.0 ohm, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.

3. Ignition ON, test for 4.8 to 5.2 volts between the 5-volt reference circuit terminal 3 and ground.

⇒	If less than 4.8 volts, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC control module.

⇒	If greater than 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the HVAC control module.

4. Install a 3-amp fused jumper wire at the signal circuit terminal 2, test for greater than 5 volts. Toggle the jumper wire between the low reference circuit terminal and the 5-volt reference circuit terminal.

⇒	If the position signal parameter is less than 5 volts, test the signal circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the HVAC control module.

5. Ignition ON, after 30 seconds verify that a test lamp illuminates between control circuit A terminal 4 and B+.
6. Ignition OFF, verify that a test lamp does not illuminate between control circuit terminal A terminal 4 and B+.

⇒	If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal replace the HVAC control module.

7. Ignition ON, after 30 seconds verify that a test lamp illuminates between control circuit B terminal 5 and B+.

⇒	If the test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.

8. Ignition OFF, verify that the test lamp does not illuminate between control circuit B terminal 5 and B+.

⇒	If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal replace the HVAC control module.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.