Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage |
|---|---|---|---|---|
Recirculation Door Control Circuit A | 1 | 1 | 1 | 1 |
Recirculation Door Control Circuit B | 1 | 1 | 1 | 1 |
5-Volt Reference | 1 | 1 | 1 | 1 |
Recirculation Door Position Signal | -- | 1 | 1 | 1 |
Recirculation Actuator Low Reference | 1 | 1 | -- | |
B+ Circuit of the HVAC Control Module | 1 | 1 | 1 | -- |
Ground Circuit of the HVAC Control Module | -- | 1 | 1 | -- |
Ignition 1 Circuit of the HVAC Control Module | -- | 1 | 1 | -- |
1. Air Recirculation Inoperative | ||||
Circuit/System Description
The recirculation 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 volt. 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.
Diagnostic Aids
Inspect the recirculation door and recirculation actuator for the following:
| • | A misaligned recirculation actuator. Refer to Recirculation Actuator Replacement . |
| • | Broken or binding linkages or recirculation door. |
| • | An obstruction that prevents the recirculation actuator from operating within the full range of motion. |
| • | Missing seals to the recirculation door. |
If the above procedure does not fix the problem test the HVAC control module ignition 1 circuit for an open or high resistance.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
- Turn ON the ignition, with the engine OFF.
- Place the blower motor switch at the maximum speed position.
- Place the mode switch in the vent or panel position.
- Place the recirculation switch in the ON position for recirculation.
- Place the recirculation switch in the OFF position for outside air position.
The flow of air should change through the vent or panel.
Circuit/System Testing
- Ignition OFF, disconnect the recirc actuator harness connector at the recirculation actuator.
- Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit terminal 1 and ground.
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 3 and ground.
- Verify the appropriate scan tool parameter is less than 3 counts.
- Install a 3A fused jumper wire between the signal circuit terminal 2 and the low reference circuit terminal 1. Verify the appropriate scan tool actuator parameter is greater than 250 counts.
- Connect a test lamp between control circuit A terminal 5 and control circuit B terminal 6.
- Command the actuator in both directions with a scan tool (air inlet door command). The test lamp should turn ON and OFF with each command.
- If all circuits test normal, replace the recirculation actuator.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module. |
| ⇒ | If less than the specified range, 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. |
| ⇒ | If greater than the specified range, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the HVAC control module. |
| ⇒ | If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module. |
| ⇒ | If the test lamp remains always ON or always OFF during either commands, test for an open, short to ground, or short to voltage on either control circuit. If the circuit tests normal, replace the HVAC control module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for HVAC control module replacement, setup, and programming |
