For 1990-2009 cars

### 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 | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Stepper Motors 12 V Reference | B023A 02, B0223 06, B0233 06, B0408 06 | B0223 06, B0233 06, B0408 06 | -- | --
Recirculation Actuator Control 1 | B0223 06 | B0223 06 | B0223 01 | 1
Recirculation Actuator Control 2 | B0223 06 | B0223 06 | B0223 01 | 1
Recirculation Actuator Control 3 | B0223 06 | B0223 06 | B0223 01 | 1
Recirculation Actuator Control 4 | B0223 06 | B0223 06 | B0223 01 | 1
1. Air Recirculation Malfunction

### Circuit/System Description

The desired position of the recirculation flap can be set with the recirculation switch at the HVAC control,. The selected value is sent to the HVAC control module via the LIN-Bus. The HVAC control module supplies a 12 V reference voltage to the stepper motor and energizes the 4 stepper motor coils with a pulsed ground signal. The stepper motor moves the recirculation flap into the selected position.

### Diagnostic Aids

Check the following mechanical fault sources:

• | Air distribution box

• | Air distribution hoses/air distribution ducts

### Reference Information

#### Schematic Reference

HVAC Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Manual HVAC Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Testing

1. Ignition ON, press and release the defrost switch. Verify the scan tool Enhanced Defrost Switch parameter changes between Active and Inactive.

⇒ | If not the specified value, replace the A26 HVAC Control.

2. Press and release the recirculation switch. Verify the scan tool Air Recirculation Mode Switch parameter changes between Active and Inactive.

⇒ | If not the specified value, replace the A26 HVAC Control.

3. If all circuits test normal, replace the M46 Recirculation Actuator and verify the M46 Recirculation Actuator can be activated and deactivated. If the M46 Recirculation Actuator cannot be activated or deactivated, replace the K33 HVAC Control Module.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Air Inlet Valve Actuator Replacement

• | Heater and Air Conditioning Control Replacement

• | Control Module References