For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Strategy Based Diagnosis

• | Diagnostic Procedure Instructions

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Recirculation Door Control Circuit A | * | * | * | --
Recirculation Door Control Circuit B | * | * | * | --
5-Volt Reference | * | * | * | --
Recirculation Door Position Signal | -- | * | * | --
Recirculation Actuator Low Reference | -- | * | * | --
B+ circuit of the HVAC control module | * | * | -- | --
Ground circuit of the HVAC control module | -- | * | -- | --
Ignition 1 circuit of the HVAC control module | -- | * | -- | --
*-Circuit 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 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.

### 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

HVAC Schematics

#### Connector End View Reference

HVAC Connector End Views

#### Description and Operation

• | Air Delivery Description and Operation

• | Air Temperature Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

• | Scan Tool Output Controls

• | Scan Tool Data List

• | Scan Tool Data Definitions

### Circuit/System Verification

1. Turn ON the ignition, with the engine OFF.
2. Place the blower motor switch at the maximum speed position.
3. Place the mode switch in the vent or panel position.
4. Place the recirculation switch in the ON position for recirculation.
5. 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

1. Ignition OFF, disconnect the harness connector at the recirculation 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 1 and the 5-volt reference circuit terminal 3.

⇒ | 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+.

⇒ | 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, test the B+ circuit of the HVAC control module for a short to ground, high resistance, or an open. If the circuit tests normal, test the HVAC control module ground circuit for a high resistance or an open. If the circuit tests normal, replace the HVAC control module.

6. Ignition OFF, verify that a test lamp does not illuminate between control circuit 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, test the B+ circuit of the HVAC control module for a short to ground, high resistance, or an open. If the circuit tests normal, test the HVAC control module ground circuit for a high resistance or an open. 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 recirculation actuator.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Control Module References for HVAC setup, programming, and replacement.

• | Recirculation Actuator Replacement