GM Service Manual Online
For 1990-2009 cars only

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.

DTC Descriptors

B0228 02: Recirculate Position Feedback Circuit Short to Ground

B0228 05: Recirculate Position Feedback Circuit Short to Battery or Open

B0228 61: Recirculate Position Circuit Actuator Stuck

B0413 02: Temperature Control 1 Feedback Circuit Short to Ground

B0413 05: Temperature Control 1 Feedback Circuit Short to Battery or Open

B0413 61: Temperature Control 1 Feedback Circuit Actuator Stuck Open

B0423 02: Temperature Control 2 Feedback Circuit Short to Ground

B0423 05: Temperature Control 2 Feedback Circuit Short to Battery or Open

B0423 61: Temperature Control 2 Circuit Actuator Stuck

B0433 02: Temperature Control 3 Feedback Circuit Short to Ground

B0433 05: Temperature Control 3 Feedback Circuit Short to Battery or Open

B0433 61: Temperature Control 3 Circuit Actuator Stuck

B3779 02: Air Flow Control 9 Feedback Circuit Short to Ground

B3779 05: Air Flow Control 9 Feedback Circuit Short to Battery or Open

B3779 61: Air Flow Control 9 Circuit Actuator Stuck

B3782 02: Air Flow Control 10 Feedback Circuit Short to Ground

B3782 05: Air Flow Control 10 Feedback Circuit Short to Battery or Open

B3782 61: Air Flow Control 10 Circuit Actuator Stuck

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Recirculation Door Ignition

B0228 02

B0228 05

B0228 05

B0228 61

Recirculation 5-Volt Reference

B0228 02, B0413 02, B0423 02, B0433 02, B0228 02, B3782 02, B3779 02

B0228 05

B0228 02, B0413 02, B0423 02, B0433 02, B0228 02, B3782 02, B3779 02

B0228 61

Recirculation Door Position Signal

B0228 02

B0228 05

B0228 05

B0228 61

Recirculation Door Control

B0228 02

B0228 05

B0228 05

B0228 61

Recirculation Low Reference

B0228 02

B0228 05

B0228 05

B0228 61

Driver Air Temperature Door Ignition

B0413 02

B0413 05

B0413 05

B0413 61

Driver Air Temperature 5-Volt Reference

B0228 02, B0413 02, B0423 02, B0433 02, B0228 02, B3782 02, B3779 02

B0413 05

B0228 02, B0413 02, B0423 02, B0433 02, B0228 02, B3782 02, B3779 02

B0413 61

Driver Air Temperature Door Position Signal

B0413 02

B0413 05

B0413 05

B0413 61

Driver Air Temperature Door Control

B0413 02

B0413 05

B0413 05

B0413 61

Driver Air Temperature Low Reference

B0413 02

B0413 05

B0413 05

B0413 61

Passenger Air Temperature Door Ignition

B0423 02

B0423 05

B0423 05

B0423 61

Passenger Air Temperature 5-Volt Reference

B0228 02, B0413 02, B0423 02, B0433 02, B0228 02, B3782 02, B3779 02

B0423 05

B0228 02, B0413 02, B0423 02, B0433 02, B0228 02, B3782 02, B3779 02

B0423 61

Passenger Air Temperature Door Position Signal

B0423 02

B0423 05

B0423 05

B0423 61

Passenger Air Temperature Door Control

B0423 02

B0423 05

B0423 05

B0423 61

Passenger Air Temperature Low Reference

B0423 02

B0423 05

B0423 05

B0423 61

Mode Door Ignition

B3779 02

B3779 05

B3779 05

B3779 61

Mode 5-Volt Reference

B0228 02, B0413 02, B0423 02, B0433 02, B0228 02, B3782 02, B3779 02

B3779 05

B0228 02, B0413 02, B0423 02, B0433 02, B0228 02, B3782 02, B3779 02

B3779 61

Mode Door Position Signal

B3779 02

B3779 05

B3779 05

B3779 61

Mode Door Control

B3779 02

B3779 05

B3779 05

B3779 61

Mode Low Reference

B3779 02

B3779 05

B3779 05

B3779 61

Auxiliary Air Temperature Door Ignition

B0433 02

B0433 05

B0433 05

B0433 61

Auxiliary Air Temperature 5-Volt Reference

B0228 02, B0413 02, B0423 02, B0433 02, B0228 02, B3782 02, B3779 02

B0433 05

B0228 02, B0413 02, B0423 02, B0433 02, B0228 02, B3782 02, B3779 02

B0433 61

Auxiliary Air Temperature Door Position Signal

B0433 02

B0433 05

B0433 05

B0433 61

Auxiliary Air Temperature Door Control

B0433 02

B0433 05

B0433 05

B0433 61

Auxiliary Air Temperature Low Reference

B0433 02

B0433 05

B0433 05

B0433 61

Auxiliary Mode Door Ignition

B3782 02

B3782 05

B3782 05

B3782 61

Auxiliary Mode 5-Volt Reference

B0228 02, B0413 02 , B0423 02, B0433 02, B0228 02, B3782 02, B3779 02

B3782 05

B0228 02, B0413 02, B0423 02, B0433 02, B0228 02, B3782 02, B3779 02

B3782 61

Auxiliary Mode Door Position Signal

B3782 02

B3782 05

B3782 05

B3782 61

Auxiliary Mode Door Control

B3782 02

B3782 05

B3782 05

B3782 61

Auxiliary Mode Low Reference

B3782 02

B3782 05

B3782 05

B3782 61

Circuit/System Description

The HVAC control module controls the HVAC door actuators to regulate the airflow through the HVAC system. Each actuator consists of an electric motor and a potentiometer. The module supplies a low reference and 5-volt reference source voltage to the potentiometer. The HVAC control module monitors the voltage drop across the potentiometer on the door position signal circuit. When the actuator shaft rotates, the voltage on the door position signal circuit changes. The control circuit uses either a 0, 2.5 or 5-volt signal to command the actuator movement. When the actuator is at rest, the control circuit value is 2.5 volts. A 0 or 5-volt control signal commands the actuator movement in opposite directions.

    • B0228 is for the recirculate actuator.
    • B0413 is for the drivers air temperature actuator.
    • B0423 is for the passenger air temperature actuator.
    • B0433 is for the auxiliary air temperature actuator.
    • B3779 is for the mode actuator.
    • B3782 is for the auxiliary mode actuator.

Conditions for Running the DTC

    • Ignition ON.
    • The HVAC module is ON.

Conditions for Setting the DTC

The actual door position differs from the commanded door position by more than 4 counts or the HVAC control module detects the door position signal circuit is less than 3 counts or greater than 253 counts.

Action Taken When the DTC Sets

The control circuit is deactivated for the appropriate actuator.

Conditions for Clearing the DTC

    • The DTC becomes history when the HVAC control module no longer detects the condition that set the DTC.
    • The history DTC will clear after 100 fault-free ignition cycles.

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component 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

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, command the appropriate actuator in both directions with a scan tool. The scan tool door position parameter reading should be between 3 and 253 counts.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the appropriate actuator.
  2. Test for less than 1 ohm between the low reference circuit terminal 7 and ground.
  3. If greater than the specified range, test the low reference circuit for an open/high resistance.
  4. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 10 and ground.
  5. If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance.
    If greater than the specified range, test the 5-volt reference circuit for a short to voltage.
  6. Verify the appropriate scan tool parameter is less than 4 counts.
  7. If greater than the specified range, test the signal circuit terminal 9 for a short to ground.
  8. Install a 3-amp fused jumper wire between the signal circuit terminal 9 and the low reference circuit terminal. Verify the appropriate scan tool parameter is greater than 250 counts.
  9. If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance.
  10. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 5 and ground.
  11. If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
  12. Install a DMM between the actuator control circuit terminal 6 and ground. While monitoring the DMM, use the scan tool to command the appropriate actuator from one direction to the other. The voltage on the control circuit should move from 0 volts in one direction to 5 volts in the other direction and 2.5 volts in the at rest state.
  13. If the voltage does not change, test the control circuit for an open, short to voltage or short to ground. If circuit tests normal replace the HVAC control module.
  14. If all circuits test normal, replace the actuator.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Recirculation Actuator Replacement
    •  Mode Actuator Replacement
    •  Temperature Valve Actuator Replacement - Left Side
    •  Temperature Valve Actuator Replacement - Right Side
    •  Auxiliary Temperature Valve Actuator Replacement
    •  Auxiliary Mode Valve Actuator Replacement
    •  Control Module References for HVAC control module replacement, setup, and programming