FREE REPAIR MANUALS & LABOR GUIDES 1982-2013 Vehicles
Courtesy of Operation CHARM: Car repair manuals for everyone.
Home >> Buick >> 2010 >> LaCrosse AWD V6-3.0L >> Repair and Diagnosis >> Heating and Air Conditioning >> Testing and Inspection >> Symptom Related Diagnostic Procedures >> HVAC - Automatic >> Air Temperature Malfunction

Air Temperature Malfunction




Air Temperature Malfunction

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 Aids

Check the following mechanical fault sources:

* Air distribution box
* Air distribution hoses/air distribution ducts

Reference Information
Schematic Reference

HVAC Schematics (C68) (HVAC Schematics (C68))HVAC Schematics (CJ2) (HVAC Schematics (CJ2))
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Automatic HVAC Description and Operation (Description and Operation)
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

Note: Check for bulletins before proceeding.

1. Ignition ON, place the blower motor switch in each speed position. Verify that the blower motor operates properly in each position.

• If the blower motor does not operate properly in all speeds, refer to Blower Motor Malfunction (Blower Motor Malfunction)

2. Using the scan tool observe the mode, temperature, air inlet and recirculation door positions. Verify the actual and commanded door positions are within 4 counts of each other.

• If not within the specified range, refer to Circuit/System Testing DTC B0223, B022A, B0233, B023A, B0408, or B0418 (B0223)

3. Engine ON, A/C ON, place the temperature control in the coldest position. Verify that cool air flows from the ducts in the vehicle.

• If the air is not cool, refer to Air Conditioning (A/C) System Performance Test (Initial Inspection and Diagnostic Overview)

4. Turn the A/C OFF and place the temperature control in the warmest position.

• If the air is insufficiently heated refer to Defrosting Insufficient (Defrosting Insufficient)

5. Engine OFF, ignition ON, cover the sunload sensor assembly with a shop towel or other suitable item. Verify the scan tool Sunload Sensor parameter changes.

• If it does not change, refer to Sun Load Sensor Circuit Malfunction.

6. Measure actual inside air temperature using a thermometer. Compare this value to the scan tool Inside Passenger Compartment Air Temp. Sensor parameter. The measured temperature should be within 5 degrees of parameter.

• If not within the specified range, refer to Passenger Compartment Air Temperature Sensor Circuit Malfunction.

7. Measure actual temperature using a thermometer at each of the duct temperature sensors. Compare this value to the appropriate scan tool Duct parameter. The measured temperature should be within 5 degrees of appropriate Duct Temperature Sensor parameter.

• If not within the specified range, refer to Duct Temperature Sensor Circuit Malfunction.

8. Ignition ON, observe the scan tool A/C Evaporator Temperature Sensor parameter. The reading should be between -39°F (-35°C) and 185°F (85°C) and change with evaporator air temperature changes.

• If not within the specified range, refer to Evaporator Air Temperature Sensor Circuit Malfunction.

Circuit/System Testing

Sun Load Sensor Circuit Malfunction
1. Ignition OFF, disconnect the harness connector at the sunload sensor.
2. Test for less than 10 ohms between the ground circuit terminal 6 and ground.

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

3. Ignition ON, test for 4.8-5.2 volts between the ground circuit terminal 6 and the signal circuit terminal 2.

• If less than the specified range, test the signal circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the HVAC control module.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the HVAC control module.

4. If all circuits test normal, test or replace the sunload sensor.

Inside Air Temperature Sensor Circuit Malfunction
1. Ignition OFF, disconnect the harness connector at the inside air temperature sensor.
2. Test for less than 10 ohms between the ground circuit terminal 6 and ground.

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

3. Ignition ON, verify the appropriate scan tool Inside Temp Sensor parameter is greater than 85°C (185°F).

• If less than the specified range, test the signal circuit terminal A 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 terminal 3 and the low reference circuit terminal 6. Verify the scan tool Temp Sensor Voltage parameter is less than -35°C (-39°F).

• If greater than the specified range, 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. If all circuits test normal, test or replace the sun load / temperature sensor.

Duct Temperature Sensor Circuit Malfunction
1. Ignition OFF, disconnect the harness connector at the appropriate temperature sensor.
2. Test for less than 10 ohms between the low reference circuit terminal B and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.

3. Ignition ON, verify the appropriate Duct Temp Sensor Actual parameter is greater than 85°C (185°F).

• If less than the specified range, test the signal circuit terminal A 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 terminal A and the low reference circuit terminal B. Verify the scan tool Duct Temp Sensor Actual parameter is less than -35°C (-39°F).

• If greater than the specified range, 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. If all circuits test normal, test or replace the appropriate temperature sensor.

Evaporator Air Temperature Sensor Circuit Malfunction
1. Ignition OFF, disconnect the harness connector at the evaporator air temperature sensor.
2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal B and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.

3. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal A and low reference circuit terminal B.

• If less than the specified range, test the signal circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the HVAC control module.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the HVAC control module.

4. If all circuits test normal, test or replace the evaporator air temperature sensor.

Repair Instructions

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

* Air Inlet Valve Actuator Replacement (CJ2) (Air Inlet Valve Actuator Replacement (CJ2))Air Inlet Valve Actuator Replacement (Without CJ2) (Air Inlet Valve Actuator Replacement (Without CJ2))
* Inside Air Valve Actuator Replacement (CJ2) (Inside Air Valve Actuator Replacement (CJ2))
* Mode Control Cam Actuator Replacement (Mode Control Cam Actuator Replacement)
* Temperature Valve Actuator Replacement - Right Side (Temperature Valve Actuator Replacement - Right Side)
* Temperature Valve Actuator Replacement - Left Side (Temperature Valve Actuator Replacement - Left Side)
* Air Conditioning Refrigerant Temperature Sensor Replacement (Service and Repair)
* Duct Air Temperature Sensor Replacement - Upper Right Side (CJ2) (Duct Air Temperature Sensor Replacement - Upper Right Side (CJ2))
* Duct Air Temperature Sensor Replacement - Upper Left Side (Duct Air Temperature Sensor Replacement - Upper Left Side)
* Duct Air Temperature Sensor Replacement - Lower Left Side (Duct Air Temperature Sensor Replacement - Lower Left Side)
* Duct Air Temperature Sensor Replacement - Lower Right Side (CJ2) (Duct Air Temperature Sensor Replacement - Lower Right Side (CJ2))
* Sun Load Temperature and Headlamp Automatic Control Ambient Light Sensor Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for HVAC control module replacement, setup, and programming

pro multis Credits:Operation CHARM About Operation CHARM