HVAC - Automatic

DTC B0228, B0413, B0423, or B3779

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.

DTC Descriptors
B0228 02
- Recirculation Position Feedback Circuit Short to Ground

B0228 04
- Recirculation Position Circuit Actuator Stuck

B0228 05
- Recirculation Position Feedback Circuit Short to Battery or Open

B0228 61
- Recirculation Position Circuit Actuator Out of Range

B0413 02
- Temperature Control 1 Feedback Circuit Short to Ground

B0413 04
- Temperature Control 1 Feedback Circuit Actuator Stuck

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

B0413 61
- Temperature Control 1 Feedback Circuit Actuator out of Range

B0423 02
- Temperature Control 2 Feedback Circuit Short to Ground

B0423 04
- Temperature Control 2 Circuit Actuator Stuck

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

B0423 61
- Temperature Control 2 Circuit Actuator Out of Range

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

B3779 04
- Air Flow Control 9 Circuit Actuator Stuck

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

B3779 61
- Air Flow Control 9 Circuit Actuator Out of Range

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 recirculation actuator.
* B0413 is for the drivers air temperature actuator.
* B0423 is for the passenger air temperature actuator.
* B3779 is for the 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 (HVAC - Automatic)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

* Air Delivery Description and Operation (Air Delivery)
* Air Temperature Description and Operation (Air Temperature)

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 (Programming and Relearning)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 10 ohms between the low reference circuit terminal 7 and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance.

3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 10 and ground.

• 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.

4. Verify the appropriate scan tool parameter is greater than 250 counts.

• If greater than the specified range, test the signal circuit terminal 9 for a short to ground.

5. 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 less than 4 counts.

• If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance.

6. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 5 and ground.

• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

7. 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.

• 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.

8. If all circuits test normal, replace the actuator.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Air Inlet Valve Actuator Replacement (Air Inlet Valve Actuator Replacement)
* Mode Valve Actuator Replacement (Mode Valve Actuator Replacement)
* Temperature Valve Actuator Replacement - Left Side (Temperature Valve Actuator Replacement - Left Side)
* Temperature Valve Actuator Replacement - Right Side (Temperature Valve Actuator Replacement - Right Side)
* Control Module References (Programming and Relearning)for HVAC control module replacement, setup, and programming