Air Recirculation Malfunction (C68)
Air Recirculation Malfunction (C68)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions 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 HVAC controls. The selected value is sent to the HVAC control module via 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 HVAC - Automatic
Connector End View Reference
Component Connector End Views Sunshade - Left (DH6)
Description and Operation
Automatic HVAC Description and Operation HVAC - Automatic
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References 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 the parameter does not change
Replace the A26 HVAC Controls.
• If the parameter changes
2. Press and release the recirculation switch. Verify the scan tool Air Recirculation Mode Switch parameter changes between Active and Inactive.
• If the parameter does not change
Replace the A26 HVAC Controls.
• If the parameter changes
3. Replace the M46 Air Recirculation Door Actuator and verify the M46 Air Recirculation Door Actuator can be put into all positions.
• If the M46 Air Recirculation Door Actuator cannot be put into all positions
Replace the K33 HVAC Control Module.
• If the M46 Air Recirculation Door Actuator can be put into all positions
4. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Air Inlet Valve Actuator Replacement Air Inlet Valve Actuator Replacement
* Heater and Air Conditioning Control Replacement Heater and Air Conditioning Control Replacement
* Control Module References Control Module References for HVAC control module replacement, programming and setup