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Air Delivery Improper

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 12V Reference

B023A 02, B0223 06, B0233 06, B0408 06

B0223 06, B0233 06, B0408 06

--

--

Mode Door Actuator Control 1

B0233 06

B0233 06

B0233 01

1

Mode Door Actuator Control 2

B0233 06

B0233 06

B0233 01

1

Mode Door Actuator Control 3

B0233 06

B0233 06

B0233 01

1

Mode Door Actuator Control 4

B0233 06

B0233 06

B0233 01

1

1. Air Distribution Malfunction

Circuit/System Description

With the defrost switch, air to foot well switch, air to windscreen switch and the air to head area switch at the HVAC controls, the desired air distribution flap position can be put in. The selected value is passed over the LIN-Bus to the HVAC control module. The HVAC control module supplies a 12 V reference voltage to the stepper motor and energises the 4 stepper motor coils with a pulsed ground signal. The stepper motor puts the air distribution flap into the selected position.

Diagnostic Aids

Check the following mechanical fault sources:

    • Air distribution box
    • Air distribution hoses/air distributing ducts

Reference Information

Schematic Reference

HVAC Schematics : Automatic

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 POWER switch. Verify the scan tool Front HVAC System Status parameter changes between Off and On.
    2. ⇒   If the parameter does not change
        Replace the A26 HVAC Controls.
    ⇓   If the parameter changes
  2. Press and release the MODE switch. Verify the scan tool Mode Switch parameter changes between Up and Inactive.
    3. ⇒   If the parameter does not change
        Replace the A26 HVAC Controls.
    ⇓   If the parameter changes
  3. Press and release the defrost switch. Verify the scan tool Enhanced Defrost Switch parameter changes between Active and Inactive.
    4. ⇒   If the parameter does not change
        Replace the A26 HVAC Controls.
    ⇓   If the parameter changes
  4. Replace the M37 Mode Door Actuator and verify the M37 Mode Door Actuator can be put into all positions.
    5. ⇒   If the M37 Mode Door Actuator cannot be put into all positions
        Replace the K33 HVAC Control Module.
    ⇓   If the M37 Mode Door Actuator can be put into all positions
  5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Heater and Air Conditioning Control Replacement
    •  Mode Control Cam Actuator Replacement : Right Hand Drive → Left Hand Drive
    • Control Module References for HVAC control module replacement, setup, and programming
   


© Copyright Chevrolet. All rights reserved
   


© Copyright Chevrolet. All rights reserved