Air Recirculation Malfunction

Air Recirculation Malfunction

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/System Description
The desired position of the recirculation flap can be set with the recirculation switch at the Radio/HVAC control. The selected value is passed to the HVAC control module via LIN-Bus. Two stepper motors are used for recirculation and fresh air control. The first stepper motor moves the air inlet flap, the second stepper motor moves the recirculation flap. In the recirculation mode the air inlet flap closes and the recirculation flap opens in order to circulate the air within the vehicle. In fresh air mode the air inlet flap opens and the recirculation flap is closed again in order to route outside air into the vehicle. The HVAC control module supplies a 12 V reference voltage to both stepper motors and energizes the appropriate 4 stepper motor coils with a pulsed ground signal. The stepper motor puts the recirculation flap and fresh air 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
Automatic 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.
2. If not the specified value, replace the A20 Radio/HVAC Controls.
3. Press and release the recirculation switch. Verify the scan tool Air Recirculation Mode Switch parameter changes between Active and Inactive.
4. If not the specified value, replace the A20 Radio/HVAC Controls.
5. Press and release the AUTO Switch. Verify the scan tool Auto HVAC Button parameter changes between Active and Inactive.
6. If not the specified value, replace the A20 Radio/HVAC Controls.
7. Verify the M46 Air Recirculation Door Motor can be put into all positions.
8. If the M46 Air Recirculation Door Motor cannot be put into all positions, replace the M46 Air Recirculation Door Motor and verify the M46 Air Recirculation Door Motor can be put into all positions. If the M46 Air Recirculation Door Motor cannot be put into all positions, replace the K33 HVAC Control Module.
9. If all circuits test normal, replace the M4 Air Inlet Actuator and verify the M4 Air Inlet Actuator can be put into all positions. If the M4 Air Inlet Actuator cannot be put into all positions, replace the K33 HVAC Control Module.

Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Inside Air Valve Actuator Replacement (Right Hand Drive)
- Air Inlet Valve Actuator Replacement (Right Hand Drive) Air Inlet Valve Actuator Replacement (Left Hand Drive)
- Instrument Panel Lower Center Trim Panel Replacement
- Control Module References for HVAC control module replacement, setup, and programming