HVAC System - Manual

DTC B0413, B4023, B0433, B3779, or B3782

Diagnostic Instructions

- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure Initial Inspection and Diagnostic Overview.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach Initial Inspection and Diagnostic Overview.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category Initial Inspection and Diagnostic Overview.

DTC Descriptors

DTC B0413 02: Temperature Control 1 Feedback Circuit Short to Ground (CJ3)

DTC B0413 05: Temperature Control 1 Feedback Circuit Short to Battery or Open (CJ3)

DTC B0413 08: Temperature Control 1 Feedback Circuit Out of Range (CJ3)

DTC B0413 61: Temperature Control 1 Feedback Circuit Actuator Stuck Open (CJ3)

DTC B0423 02: Temperature Control 2 Feedback Circuit Short to Ground (CJ3)

DTC B0423 05: Temperature Control 2 Feedback Circuit Short to Battery or Open (CJ3+C67)

DTC B0423 08: Temperature Control 2 Feedback Circuit Out of Range (CJ3+C67)

DTC B0423 61: Temperature Control 2 Circuit Actuator Stuck (CJ3+C67)

DTC B0433 02: Temperature Control 3 Feedback Circuit Short to Ground (CJ3)

DTC B0433 05: Temperature Control 3 Feedback Circuit Short to Battery or Open (CJ3)

DTC B0433 08: Temperature Control 3 Feedback Circuit Out of Range (CJ3)

DTC B0433 61: Temperature Control 3 Circuit Actuator Stuck (CJ3)

DTC B3782 02: Air Flow Control 10 Feedback Circuit Short to Ground (CJ3)

DTC B3782 05: Air Flow Control 10 Feedback Circuit Short to Battery or Open (CJ3)

DTC B3782 08: Air Flow Control 10 Feedback Circuit Out of Range (CJ3)

DTC B3782 61: Air Flow Control 10 Circuit Actuator Stuck (CJ3)

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.

- DTC B0413 is for the drivers air temperature actuator
- DTC B0423 is for the passenger air temperature actuator
- DTC B0433 is for the auxiliary air temperature actuator
- DTC B3782 is for the auxiliary mode actuator
- DTC B3779 is for the mode actuator

Conditions for Running the DTC

- The ignition is ON.
- Ignition voltage is between 9-16 volts.
- 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 6 counts or greater than 250 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.
- The DTC can be cleared with a scan tool.

Reference Information

Schematic Reference

HVAC Schematics Electrical Diagrams

Connector End View Reference

HVAC Connector End Views Connector Views

Electrical Information Reference

- Circuit Testing Component Tests and General Diagnostics
- Connector Repairs Component Tests and General Diagnostics
- Testing for Intermittent Conditions and Poor Connections Component Tests and General Diagnostics
- Wiring Repairs Component Tests and General Diagnostics

Scan Tool Reference

- Scan Tool Data List Scan Tool Testing and Procedures
- Scan Tool Output Controls Scan Tool Testing and Procedures

Circuit/System Verification

Ignition ON, command the appropriate actuator to 100 percent with a scan tool. The scan tool should display between 224 and 230 counts on the mode actuator, all other actuators should display between 199 and 205 counts.

Circuit/System Testing

1. Ignition OFF, disconnect the appropriate actuator and test for less than 1 ohm between the low reference circuit and ground.

-> If greater than 1 ohm, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.

2. Ignition ON, test for 4.4-5.2 volts between the 5-volt reference circuit and ground.

-> If less than 4.4 volts, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC control module.

-> If greater than 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the HVAC control module.

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

-> If less than 250 counts, test the signal circuit for a short to ground. If the circuit tests normal, replace the HVAC Control Module.

4. Install a 3-amp fused jumper wire between the signal circuit and the low reference circuit terminal. Verify the appropriate scan tool parameter is less than 4 counts.

-> If more than 4 counts, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.

5. Ignition ON, verify that a test lamp illuminates between the ignition 3 circuit and ground.

-> If the test lamp does not illuminate, test the ignition 3 circuit for a short to ground an open/high resistance.

6. Install a DMM between the actuator control circuit and ground. While monitoring the DMM use the scan tool to command the appropriate actuator from one direction to the other. If the voltage on the control circuit moves 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.

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

- HVAC System Control Module Programming and Setup Programming and Relearning
- Auxiliary Heating, Ventilation, and Air Conditioning Control Module Programming and Setup Programming and Relearning
- Air Inlet Valve Actuator Replacement Service and Repair
- Mode Valve Actuator Replacement Service and Repair
- Temperature Valve Actuator Replacement - Left Side Service and Repair
- Temperature Valve Actuator Replacement - Right Side Service and Repair
- Auxiliary Temperature Valve Actuator Replacement Service and Repair
- Auxiliary Mode Valve Actuator Replacement Service and Repair