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HVAC System - Automatic Buick Enclave I

Automatic HVAC System 21 illustrations ~14573 words

Fastener Tightening Specifications

ApplicationSpecification
MetricEnglish
Actuator Mounting Screws1.5 N.m13 lb in
HVAC Control Module Mounting Screws2 N.m17 lb in

Fastener Tightening Specifications

Sensor Resistance Table

TemperatureAmbient Air Temp SensorInside Air Temp Sensor or Duct Air Temperature Sensors (Upper & Lower, LH & RH) or Evaporator Air Temperature Sensor
°C°F(K ohms)(K ohms)
4040333.692.8
3531241.166.9
3022176.148.8
2513129.935.9
20496.826.8
15572.820.1
101455.315.3
52342.311.7
03232.79.0
54125.47.0
105019.95.5
155915.74.3
206812.53.4
257710.02.8
30868.12.2
35956.51.8
401045.31.5
451134.41.2
501223.61.0
551313.00.8
601402.50.7
651402.10.6
701581.80.5

Sensor Resistance Table

Scheme 58

Scheme 58: Power, Ground, Blower Control, Serial Data, and Sunload Sensor
Scheme 58: Power, Ground, Blower Control, Serial Data, and Sunload Sensor

Scheme 59

Scheme 59: Actuators
Scheme 59: Actuators

Scheme 60

Scheme 60: Sensors
Scheme 60: Sensors

Scheme 61

Scheme 61: Compressor Controls
Scheme 61: Compressor Controls

Scheme 62

Scheme 62: Rear HVAC
Scheme 62: Rear HVAC

Diagnostic Code Index

DTCDescription
DTC B0158DTC B0158 02 Outside Air Temperature Sensor Circuit Short to Ground DTC B0158 05 Outside Air Temperature Sensor Circuit Short to Battery or Open
DTC B0163DTC B0163 02 Passenger Compartment Temperature Sensor Circuit Short to Ground DTC B0163 05 Passenger Compartment Temperature Sensor Circuit Short to Battery or Open
DTC B0173, B0178, B0509, or B0514DTC B0173 02 Output Air Temperature Sensor 1 Circuit Short to Ground DTC B0173 05 Output Air Temperature Sensor 1 Circuit Short to Battery or Open DTC B0178 02 Output Air Temperature Sensor 2 Circuit Short to Ground DTC B0178 05 Output Air Temperature Sensor 2 Circuit Short to Battery or Open DTC B0509 02 Output Air Temperature Sensor 3 Circuit Short to Ground DTC B0509 05 Output Air Temperature Sensor 3 Circuit Short to Battery or Open DTC B0514 02 Output Air Temperature Sensor 4 Circuit Short to Ground DTC B0514 05 Output Air Temperature Sensor 4 Circuit Short to Battery or Open
DTC B0183 or B0188DTC B0183 02 Solar Load Sensor 1 Circuit Short to Ground DTC B0183 05 Solar Load Sensor 1 Circuit Short to Battery or Open DTC B0188 02 Solar Load Sensor 2 Circuit Short to Ground DTC B0188 05 Solar Load Sensor 2 Circuit Short to Battery or Open
DTC B0228, B0413, B0423, B0433, B3779, or B3782DTC B0228 02 Recirculate Position Feedback Circuit Short to Ground DTC B0228 04 Recirculate Position Feedback Circuit Open DTC B0228 05 Recirculate Position Feedback Circuit Short to Battery or Open DTC B0228 08 Recirculate Position Circuit Actuator Stalled DTC B0228 61 Recirculate Position Circuit Actuator Stuck DTC B0413 02 Temperature Control 1 Feedback Circuit Short to Ground DTC B0413 04 Temperature Control 1 Feedback Circuit Open DTC B0413 05 Temperature Control 1 Feedback Circuit Short to Battery or Open DTC B0413 08 Temperature Control 1 Feedback Circuit Actuator Stalled DTC B0413 61 Temperature Control 1 Feedback Circuit Actuator Stuck Open DTC B0423 02 Temperature Control 2 Feedback Circuit Short to Ground DTC B0423 04 Temperature Control 2 Feedback Circuit Open DTC B0423 05 Temperature Control 2 Feedback Circuit Short to Battery or Open DTC B0423 08 Temperature Control 2 Circuit Actuator Stalled DTC B0423 61 Temperature Control 2 Circuit Actuator Stuck DTC B0433 02 Temperature Control 3 Feedback Circuit Short to Ground DTC B0433 04 Temperature Control 3 Feedback Circuit Open DTC B0433 05 Temperature Control 3 Feedback Circuit Short to Battery or Open DTC B0433 08 Temperature Control 3 Circuit Actuator stalled DTC B0433 61 Temperature Control 3 Circuit Actuator Stuck DTC B3779 02 Air Flow Control 9 Feedback Circuit Short to Ground DTC B3779 04 Air Flow Control 9 Feedback Circuit Open DTC B3779 05 Air Flow Control 9 Feedback Circuit Short to Battery or Open DTC B3779 08 Air Flow Control 9 Circuit Actuator stalled DTC B3779 61 Air Flow Control 9 Circuit Actuator Stuck DTC B3782 02 Air Flow Control 10 Feedback Circuit Short to Ground DTC B3782 04 Air Flow Control 10 Feedback Circuit Open DTC B3782 05 Air Flow Control 10 Feedback Circuit Short to Battery or Open DTC B3782 08 Air Flow Control 10 Circuit Actuator Stalled DTC B3782 61 Air Flow Control 10 Circuit Actuator Stuck
DTC B1023DTC B1023 05 Integral Switch Performance Short to Ground DTC B1023 06 Integral Switch Performance Short to Battery or Open DTC B1023 61 Integral Switch Performance Signal Invalid
DTC B3933DTC B3933 02 Evaporator Air Temperature Sensor Short to Ground DTC B3933 05 Evaporator Air Temperature Sensor Short to Battery or Open
DTC P0532 or P0533DTC P0532 Air Conditioning A/C Refrigerant Pressure Sensor Circuit Low Voltage DTC P0533 Air Conditioning A/C Refrigerant Pressure Sensor Circuit High Voltage
DTC P0645DTC P0645 A/C Clutch Relay Control Circuit

DIAGNOSTIC CODE INDEX

Diagnostic Instructions

  1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Ambient Air Temperature Sensor SignalB0158 02B0158 05B0158 05
Low ReferenceB0173 05, B0158 05, B0163 05, B0509 05B0173 05, B0158 05, B0163 05, B0509 05

Circuit/System Description

The HVAC control module monitors the ambient air temperature sensor with a low reference circuit and 5-volt signal circuit. The HVAC control module monitors the voltage drop across the sensor, which is proportional to temperature. When the ambient air temperatures are cold, the resistance of the sensor is high and the voltage signals are high. When the ambient air temperatures are hot, the resistance of the sensors is low and the voltage signals are low. The HVAC control module converts the voltage value to a temperature value of Celsius and Fahrenheit that will be displayed by the driver information center (DIC).

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Setting the DTC

  1. The HVAC control module detects the sensor signal circuit is less than -35°C (-39°F).
  2. The HVAC control module detects the sensor signal circuit is more than 85°C (185°F) .

Action Taken When the DTC Sets

The HVAC control module uses a default air temperature value for further automatic control calculations. The default values are not displayed on the scan tool.

Conditions for Clearing the DTC

  1. The DTC will become history if the HVAC control module no longer detects a failure.
  2. The history DTC will clear after 100 fault-free ignition cycles.

Reference Information

Schematic Reference

Connector End View Reference

Description and Operation

  1. «Air Temperature Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)
  2. «Air Delivery Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)

Electrical Information Reference

  1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, observe the scan tool Outside Air Temp. Sensor Raw parameter. The reading should be between -35°C (-39°F) and 85°C (185°F) and change with ambient air temperature changes.

Circuit/System Testing

IMPORTANTAn instant Outside Air Temperature (OAT) update must be performed by pressing the A/C and Recirc buttons at the same time before and after the system has been serviced to update the filtered ambient air temperature sensor.
  1. Ignition OFF, disconnect the harness connector at the ambient air temp 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, verify the scan tool Outside Air Temp. Sensor Raw parameter is less than -35°C (-39°F). If greater 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 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Outside Air Temp. Sensor Raw parameter is greater than 85°C (185°F). If less 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 ambient air temp sensor.

Component Testing

  1. Test the ambient air temperature sensor by varying the sensor temperature while monitoring the sensor resistance.
  2. Compare the readings with the «Sensor Resistance Table»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__sensor-resistance-table) and verify that the resistance is within 5 percent of the specification. If not within the specified range, replace the sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Ambient Air Temperature Sensor Replacement (Enclave,Traverse)»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic) , «Ambient Air Temperature Sensor Replacement (Acadia)»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  2. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Inside Air Temperature Sensor SignalB0163 02B0163 05B0163 05
Low ReferenceB0173 05, B0158 05, B0163 05, B0509 05B0173 05, B0158 05, B0163 05, B0509 05

The HVAC control module supplies the inside air temperature sensor with a low reference circuit and 5-volt signal circuit. The HVAC control module determines the voltage drop across the sensor, which is proportional to temperature. As the air temperature increases, the sensor resistance decreases and the voltage signal decreases. As the air temperature decreases, the sensor resistance increases and the voltage signal increases.

Passenger compartment temperature sensor refers to the inside air temperature sensor.

The ignition is turned ON.

The HVAC control module detects the inside air temperature sensor signal circuit is less than -36°C (-38°F) or greater than 215°C (419°F) for greater than 15 seconds.

The system operates using a default value.

  1. The DTC will become history if the HVAC control module no longer detects the condition that set the DTC.
  2. The history DTC will clear after 100 fault-free ignition cycles.

Schematic Reference

Connector End View Reference

Description and Operation

  1. «Air Temperature Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)
  2. «Air Delivery Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)

Electrical Information Reference

  1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the scan tool Inside Air Temperature Sensor parameter. The reading should be between -35°C (-39°F) and 98°C (208°F) and change with inside air temperature changes.

  1. Ignition OFF, disconnect the harness connector at the inside air temp 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, verify the scan tool inside Air Temp. Sensor parameter is less than -35°C (-39°F). If greater 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 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Inside Air Temp. Sensor parameter is greater than 85°C (185°F). If less 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 inside air temp sensor.
  1. Test the inside air temperature sensor by varying the sensor temperature while monitoring the sensor resistance.
  2. Compare the readings with the «Sensor Resistance Table»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__sensor-resistance-table) and verify that the resistance is within 5 percent of the specification. If not within the specified range, replace the sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Inside Air Temperature Sensor Aspirator Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  2. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module replacement, setup and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Upper Left Air Temperature Sensor SignalB0173 02B0173 05B0173 05
Upper Right Air Temperature Sensor SignalB0509 02B0509 05B0509 05
Lower Left Air Temperature Sensor SignalB0178 02B0178 05B0178 05
Lower Right Air Temperature Sensor SignalB0514 02B0514 05B0514 05
Low ReferenceB0173 05, B0158 05, B0163 05, B0509 05, B0178 05, B0514 05, B3933 05B0173 05, B0158 05, B0163 05, B0509 05, B0178 05, B0514 05, B3933 05

The HVAC control module supplies the air duct temperature sensors with a low reference circuit and 5-volt signal circuit. The HVAC control module determines the voltage drop across the sensor, which is proportional to temperature. As the air temperature increases, the sensor resistance decreases and the voltage signal decreases. As the air temperature decreases, the sensor resistance increases and the voltage signal increases.

  1. DTC B0173 output Air Temperature Sensor 1 refers to the upper left air duct temperature sensor
  2. DTC B0178 output Air Temperature Sensor 2 refers to the lower left air duct temperature sensor
  3. DTC B0509 output Air Temperature Sensor 3 refers to the upper right air duct temperature sensor
  4. DTC B0514 output Air Temperature Sensor 4 refers to the lower right air duct temperature sensor

The ignition is turned ON.

The HVAC control module detects the inside air temperature sensor signal circuit is less than -36°C (-38°F) or greater than 215°C (419°F) for greater than 15 seconds.

The system operates using a default value.

  1. The DTC will become history if the HVAC control module no longer detects the condition that set the DTC.
  2. The history DTC will clear after 100 fault-free ignition cycles.

Schematic Reference

Connector End View Reference

Description and Operation

  1. «Air Temperature Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)
  2. «Air Delivery Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)

Electrical Information Reference

  1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the appropriate scan tool air duct temperature sensor. The reading should be between -35°C (-39°F) and 98°C (208°F) and change with duct air temperature changes.

IMPORTANTIf an air duct temperature sensor has an out of range condition caused by a short to voltage, short to ground, or an open/high resistance, the scan tool will display the same value: 39°F (4°C).
  1. Ignition OFF, disconnect the harness connector at the appropriate air duct temperature sensor.
  2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal 2 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 1 and the low reference 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 air duct temperature sensor.
  1. Test the air duct temperature sensor by varying the sensor temperature while monitoring the sensor resistance.
  2. Compare the readings with the «Sensor Resistance Table»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__sensor-resistance-table) and verify that the resistance is within 5 percent of the specification. If not within the specified range, replace the sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Duct Air Temperature Sensor Replacement - Upper Right Side»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  2. «Duct Air Temperature Sensor Replacement - Upper Left Side»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  3. «Duct Air Temperature Sensor Replacement - Lower Left Side»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  4. «Duct Air Temperature Sensor Replacement - Lower Right Side»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  5. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module replacement, setup and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Left Sunload Sensor SignalB0183 02B0183 05B0183 05
Right Sunload Sensor SignalB0188 02B0188 05B0188 05
Sunload sensors Ground CircuitB0183 05, B0188 05B0183 05, B0188 05

Circuit Description

The sunload sensor is a 2-wire photo diode. The vehicle uses left and right sunload sensors. The two sensors are integrated into the sunload sensor assembly along with the ambient light sensor. Ground and signal circuits enable the sensors to operate. As the sunload increases, the sensor signal decreases. The sensor signal varies between 0 and 5 volts. The HVAC control module converts the signal to a range between 0 and 255 counts. The sunload sensor provides the HVAC control module with a measurement of the amount of light shining on the vehicle. Bright or high intensity light causes the vehicles interior temperature to increase. The HVAC system compensates for the increased temperature by diverting additional cool air into the vehicle.

The following DTCs are for the left and right sunload sensors.

  1. B0183 is for the left sunload sensor.
  2. B0188 is for the right sunload sensor.

The ignition is ON.

The HVAC control module detects the signal circuit is less than 5 counts or greater than 250 counts.

  1. The driver information center (DIC) will display SERVICE A/C SYSTEM.
  2. The system will operate as if no sunload condition exists.
  1. The DTC will become history if the HVAC control module no longer detects the condition that set the DTC.
  2. The history DTC will clear after 100 fault-free ignition cycles.

Schematic Reference

Connector End View Reference

Description and Operation

  1. «Air Temperature Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)
  2. «Air Delivery Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)

Electrical Information Reference

  1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the appropriate scan tool Sunload Sensor parameter. The reading should be between 5 and 250 counts and change with sunlight intensity.

IMPORTANTIf a solar load sensor has an out of range condition caused by a short to voltage, short to ground, or an open/high resistance, the scan tool will display the same value: 225 counts.
  1. Ignition OFF, disconnect the harness connector at the sunload sensor.
  2. Test for less than 10 ohms between the ground circuit terminal C 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 appropriate signal circuit terminal and the ground circuit terminal C . Left solar load sensor circuit terminal A. Right solar load sensor 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 sunload sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Daytime Running Lamp (DRL) Ambient Light Sensor Replacement (Without UV6)»(/buick/enclave/i-2007-2013/remont/exterior-lights/#lighting-system) , «Daytime Running Lamp (DRL) Ambient Light Sensor Replacement (With UV6)»(/buick/enclave/i-2007-2013/remont/exterior-lights/#lighting-system)
  2. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The actuators operate using 5 circuits. A 5-volt reference, low reference, signal circuit and two bi-directional 0 or 12 volt control circuits. The HVAC control module supplies a low reference and 5-volt reference to the potentiometer. The HVAC control module monitors the voltage drop across the potentiometer on the door position signal circuit. As the actuator door changes position the door position signal circuit voltage also changes. The two bi-directional control circuits enable the actuator to operate. Both circuits are set to 0 volts when the HVAC control module detects, from the feedback potentiometer, that the actuator is in the desired position. In order to move the actuator, the HVAC control module switches the appropriate control circuit to 12 volts.

  1. DTC B0228 is for the recirculate actuator
  2. DTC B0413 is for the left air temperature actuator
  3. DTC B0423 is for the right air temperature actuator
  4. DTC B0433 is for the auxiliary air temperature actuator
  5. DTC B3782 is for the auxiliary mode actuator
  6. DTC B3779 is for the mode actuator
  1. The ignition is ON.
  2. The HVAC module is ON.

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.

The control circuit is deactivated for the appropriate actuator.

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

Schematic Reference

Connector End View Reference

Description and Operation

  1. «Air Delivery Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)
  2. «Air Temperature Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)

Electrical Information Reference

  1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

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.

  1. Ignition OFF, disconnect all external devices to include the scan tool and battery charger. It will take more than 10 minutes for all vehicle systems to power down.
  2. Disconnect the harness connector at the appropriate actuator.
  3. Test for less than 10 ohms between the low reference circuit terminal 8 and ground.
  4. 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.
  5. 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 the circuit tests normal, replace the HVAC control module. If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the HVAC control module.
  6. Verify the scan tool Door Position parameter is greater than 250 counts. If less than the specified range, test the signal circuit terminal 9 for a short to ground. If the circuit tests normal, replace the HVAC control module.
  7. Install a 3A fused jumper wire between the signal circuit terminal 9 and the low reference circuit terminal 8. Verify the scan tool Door Position parameter is less than 3 counts. 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.
  8. Ignition ON, test for less than 10 ohms between the control circuit terminal 5 and ground. If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuit tests normal, replace the HVAC control module.
  9. Ignition ON, test for less than 10 ohms between the control circuit terminal 6 and ground. If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuit tests normal, replace the HVAC control module.
  10. Connect a test lamp between control circuit terminal 5 and control circuit terminal 6.
  11. Ignition ON, command the appropriate actuator door in both directions with a scan tool. The test lamp should turn ON and OFF when commanded in both directions. If the test lamp remains OFF during either of the commands, test for a short to ground on either control circuit. If the circuits test normal, replace the HVAC control module.
  12. If both circuits test normal, test or replace the actuator.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Air Inlet Valve Actuator Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  2. «Mode Valve Actuator Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  3. «Temperature Valve Actuator Replacement - Left Side»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  4. «Temperature Valve Actuator Replacement - Right Side»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  5. «Auxiliary Temperature Valve Actuator Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  6. «Auxiliary Mode Valve Actuator Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  7. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module and HVAC Auxiliary control module or rear seat audio (RSA) replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

This DTC will be set by internal fault inside the HVAC control module for a stuck or shorted control button.

Battery voltage is between 9-16 volts and data link communications operate normally.

The HVAC control module has internal fault inside the HVAC control module for a stuck or shorted control button.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Schematic Reference

Connector End View Reference

Description and Operation

  1. «Air Delivery Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)
  2. «Air Temperature Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)

Electrical Information Reference

  1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Reprogram the HVAC control module. The module should successfully reprogram. If the module will not reprogram, replace the HVAC control module that set the DTC.
  2. With a scan tool, clear the DTC.
  3. Ignition OFF.
  4. Wait 60 seconds, then recheck for DTCs. DTC B1023 should not set. If DTC B1023 sets, replace the module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for control module replacement, setup, and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Evaporator Temperature Sensor SignalB3933 02B3933 05B3933 05
Low ReferenceB3933 05, B0178 05, B0514 05B3933 05, B0178 05, B0514 05

The HVAC control module supplies the evaporator air temperature sensor with a low reference circuit and 5-volt signal circuit. The HVAC control module determines the voltage drop across the sensor, which is proportional to temperature. As the air temperature increases, the sensor resistance decreases and the voltage signal decreases. As the air temperature decreases, the sensor resistance increases and the voltage signal increases.

The ignition is turned ON.

The HVAC control module detects the evaporator air temperature sensor signal circuit is less than -36°C (-38°F) or more than 215°C (419°F) for more than 15 seconds.

The A/C compressor will be disabled.

  1. The DTC will become history if the HVAC control module no longer detects a failure.
  2. The history DTC will clear after 100 fault-free ignition cycles.

Schematic Reference

Connector End View Reference

Description and Operation

  1. «Air Temperature Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)
  2. «Air Delivery Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)

Electrical Information Reference

  1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the scan tool A/C Evaporator Temperature Sensor parameter. The reading should be between -39°F (-35°C) and 208°F (98°C) and change with evaporator air temperature changes.

IMPORTANTIf the evaporator air temperature sensor has an out of range condition caused by a short to voltage, short to ground, or an open/high resistance, the scan tool will display the same value: 11°C (51°F).
  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 2 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 1 and low reference 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 evaporator air temperature sensor.
  1. Test the evaporator air temperature sensor by varying the sensor temperature while monitoring the sensor resistance.
  2. Compare the readings with the «Sensor Resistance Table»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__sensor-resistance-table) and verify that the resistance is within 5 percent of the specification. If not within the specified range, replace the sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Evaporator Air Temperature Sensor Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
  2. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
5-Volt ReferenceP0532P0532P0533
A/C Refrigerant Pressure Sensor SignalP0532P0533P0533
Low ReferenceP0532P0533

The engine control module (ECM) monitors the high side refrigerant pressure through the A/C refrigerant pressure sensor. The ECM supplies a 5-volt reference and a low reference to the sensor. Changes in the A/C refrigerant pressure cause the A/C refrigerant pressure sensor signal to the ECM to vary. When the pressure is low, the signal voltage is low. When the pressure is high, the ECM commands the cooling fans on. When pressure is too high or too low, the ECM will not allow the A/C compressor clutch to engage.

The engine is running.

  1. The ECM detects that the A/C pressure is less than 1 psi (0.01 volt) sets DTC P0532.
  2. The ECM detects that the A/C pressure is greater than 425 psi (4.90 volts) sets DTC P0533.
  1. The ECM will not illuminate the malfunction indicator lamp (MIL).
  2. The ECM stores the failure records.
  3. The A/C compressor clutch is disabled.
  1. The DTC will become history if the ECM no longer detects a failure.
  2. The history DTC will clear after 40 consecutive ignition cycles have occurred without a malfunction.

Diagnostic Aids

A malfunction within the refrigerant system causing high pressure can cause DTC P0533 to set.

Schematic Reference

Connector End View Reference

Description and Operation

  1. «Air Temperature Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)
  2. «Air Delivery Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)

Electrical Information Reference

  1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the scan tool A/C Refrigerant Pressure Sensor parameter. The reading should be between 0.1 volts (1 psi) and 4.90 volts (425 psi) and change with A/C refrigerant pressure changes.

  1. Ignition OFF, disconnect the harness connector at the A/C refrigerant pressure sensor.
  2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal 1 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 ECM.
  3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 2 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 the circuit tests normal, replace the ECM. If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  4. Verify the scan tool A/C High Side Pressure Sensor parameter is less than 0.1 volts (1 psi). If greater than the specified range, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the ECM.
  5. Install a 3A fused jumper wire between the signal circuit terminal 3 and the 5-volt reference circuit terminal 2. Verify the scan tool A/C Refrigerant High Side Pressure Sensor parameter is greater than 4.90 volts (425 psi). If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
  6. If all circuits test normal, test or replace the A/C refrigerant pressure sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
  2. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for the ECM replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
A/C Relay Switch B+11
A/C Relay Coil Ignition11
A/C Relay Switched Output Control112
A/C Compressor Clutch Relay ControlP0645P0645P0645
A/C Compressor Clutch Ground1
1. A/C Compressor Inoperative 2. A/C Compressor Always On

Circuit System Description

When the A/C switch is pressed, the HVAC control module sends a serial data message to the ECM. This input will request the engine control module (ECM) to ground the A/C compressor clutch relay control circuit, which will switch the A/C CMPRSR CLUTCH relay on. With the relay contacts closed, battery voltage is supplied to the A/C compressor clutch assembly.

  1. The ignition voltage is between 11-18 volts.
  2. The engine speed is greater than 600 RPM.
  3. An A/C request is made.

Conditions for Setting the DTCs

The ECM detects an open on the control circuit of the A/C compressor clutch relay when commanded OFF with the engine in crank or run status.

The ECM will store conditions which were present when the DTC set as Failure Records data only. This information will not be stored as Freeze Frame data.

A History DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction.

The following conditions must be met in order for the ECM to turn on the compressor clutch

  1. Battery voltage is between 9-18 volts.
  2. Engine coolant temperature (ECT) is less than 123°C (253°F).
  3. Engine speed is greater than 600 RPM.
  4. Engine speed is less than 4,760 RPM.
  5. A/C high side pressure is between 269-2929 kPa (39-425 psi)-Refer to «Air Conditioning (A/C) System Performance Test»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__air-conditioning-ac-system-performance-test) .
  6. Throttle position is less than 100 percent.
  7. Evaporator temperature is greater than 0°C (32°F).
  8. ECM does not detect excessive torque load.
  9. ECM does not detect insufficient idle quality.
  10. The ambient temperature is above 1°C (34°F).

Schematic Reference

Connector End View Reference

Description and Operation

  1. «Air Delivery Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)
  2. «Air Temperature Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)

Electrical Information Reference

  1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition OFF, disconnect the A/C relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 86 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the ignition circuit terminal 85 and ground. If the test lamp does not illuminate, test the ignition circuit for a short to ground or a open/high resistance. If the circuit tests normal and ignition circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.
  4. Verify that a test lamp illuminates between the relay B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or a open/high resistance. If the circuit tests normal and B+ circuit fuse is open, replace the A/C Clutch Relay.
  5. Disconnect the harness connector at the A/C clutch coil.
  6. Test for less than 1 ohm between the ground circuit terminal ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Connect the harness connector at the A/C clutch coil.
  8. Connect a 10-amp fused jumper wire between the B+ circuit terminal 30 and control circuit terminal 87. Verify the A/C clutch is activated. If the A/C clutch does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the A/C clutch.
  9. Connect a test lamp between the ignition circuit terminal 85 and the control circuit terminal 86.
  10. Command the A/C Relay output function ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM. If the test lamp is always OFF, test the control circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the ECM.
  11. If all circuits test normal, test or replace the A/C clutch relay.

Relay Test

  1. Ignition OFF, disconnect the A/C relay.
  2. Test for 60-200 ohms between terminal 85 and 86. If the resistance is not within the specified range, replace the relay.
  3. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified value, replace the relay.
  4. Install a 15A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Air Conditioning Compressor Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
  2. «Relay Replacement (Within an Electrical Center)»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions__relay-replacement-within-an-electrical-center) , «Relay Replacement (Attached to Wire Harness)»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
  3. «Air Conditioning Clutch Assembly Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
  4. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module and ECM replacement, setup, and programming

Symptoms - HVAC Systems - Automatic

IMPORTANTReview the system operation in order to familiarize yourself with the system functions. Refer to the following procedures: Air Delivery Description and Operation Air Temperature Description and Operation

Visual/Physical Inspection

  1. Inspect for aftermarket devices which could affect the operation of the HVAC System. Refer to «Checking Aftermarket Accessories»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__checking-aftermarket-accessories) .
  2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
  3. Verify the A/C compressor clutch turns freely and is not seized.
  4. The A/C compressor will not operate in cold outside air temperatures. Refer to «Air Temperature Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation) .
  5. The following could cause window fogging: Wet carpet or mats High humidity Interior water leak Blocked A/C evaporator drain tube Maximum passenger capacity Blocked body pressure relief valves
  6. Inspect the air distribution system for causes of reduced air flow: Obstructed or dirty passenger compartment air filter, if equipped Blocked or damaged air inlet or outlet vents

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

  1. «Blower Motor Malfunction»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  2. «Auxiliary Blower Motor Malfunction»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  3. «Air Conditioning Compressor Malfunction»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  4. «Air Temperature Malfunction»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  5. «Leak Testing»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__leak-testing)
  6. «Noise Diagnosis - HVAC Module»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__noise-diagnosis-hvac-module)
  7. «Noise Diagnosis - Air Conditioning (A/C) System»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__noise-diagnosis-air-conditioning-ac)
  8. «Noise Diagnosis - Blower Motor»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__noise-diagnosis-blower-motor)
  9. «Odor Diagnosis»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__odor-diagnosis)
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
A/C Relay Switch B+11
A/C Relay Coil Ignition11
A/C Relay Switched Output Control112
A/C Compressor Clutch Relay ControlP0645P0645P0645
A/C Compressor Clutch Ground1
1. A/C Compressor Inoperative 2. A/C Compressor Always On

When the A/C switch is pressed, the HVAC control module sends a serial data message to the ECM. This input will request the engine control module (ECM) to ground the A/C compressor clutch relay control circuit, which will switch the A/C CMPRSR CLUTCH relay on. With the relay contacts closed, battery voltage is supplied to the A/C compressor clutch assembly.

The following conditions must be met in order for the ECM to turn on the compressor clutch

  1. Battery voltage is between 9-18 volts
  2. Engine coolant temperature (ECT) is less than 123°C (253°F)
  3. Engine speed is greater than 600 RPM
  4. Engine speed is less than 4,760 RPM
  5. A/C high side pressure is between 2929-269 kPa (39-425 psi) «Air Conditioning (A/C) System Performance Test»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__air-conditioning-ac-system-performance-test)
  6. Throttle position is less than 100 percent
  7. Evaporator temperature is greater than 0°C (32°F)
  8. ECM does not detect excessive torque load
  9. ECM does not detect insufficient idle quality
  10. The ambient temperature is above 1°C (34°F)

Schematic Reference

Connector End View Reference

Description and Operation

  1. «Air Temperature Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)
  2. «Air Delivery Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)

Electrical Information Reference

  1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Engine running place the mode switch in the defrost position. The A/C compressor clutch should engage.

  1. If the clutch does not engage refer to «Air Conditioning (A/C) System Performance Test»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__air-conditioning-ac-system-performance-test)
  1. Ignition OFF, disconnect the A/C relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 86 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the ignition circuit terminal 85 and ground. If the test lamp does not illuminate, test the ignition circuit for a short to ground or a open/high resistance. If the circuit tests normal and ignition circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.
  4. Verify that a test lamp illuminates between the relay B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or a open/high resistance. If the circuit tests normal and B+ circuit fuse is open, replace the A/C Clutch Relay.
  5. Disconnect the harness connector at the A/C clutch coil.
  6. Test for less than 1 ohm between the ground circuit terminal ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Connect the harness connector at the A/C clutch coil.
  8. Connect a 10-amp fused jumper wire between the B+ circuit terminal 30 and control circuit terminal 87. Verify the A/C clutch is activated. If the A/C clutch does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the A/C clutch.
  9. Connect a test lamp between the ignition circuit terminal 85 and the control circuit terminal 86.
  10. Command the A/C Relay output function ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM. If the test lamp is always OFF, test the control circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the ECM.
  11. If all circuits test normal, test or replace the A/C clutch relay.

Relay Test

  1. Ignition OFF, disconnect the A/C relay.
  2. Test for 60-200 ohms between terminal 85 and 86. If the resistance is not within the specified range, replace the relay.
  3. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified value, replace the relay.
  4. Install a 15A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Air Conditioning Compressor Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
  2. «Relay Replacement (Within an Electrical Center)»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions__relay-replacement-within-an-electrical-center) , «Relay Replacement (Attached to Wire Harness)»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
  3. «Air Conditioning Clutch Assembly Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
  4. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module and ECM replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Blower Motor Control Module B+11
Blower Motor B+11
Blower Motor Speed Control211
Blower Motor Control211
Ground1
1. Blower Motor Inoperative 2. Blower Motor Always On

The blower motor control module is an interface between the HVAC control module and the blower motor. The blower motor speed control, battery positive and ground circuits enable the control module to operate. The HVAC control module provides a pulse width modulation (PWM) signal to the blower motor speed control module in order to command the blower motor speed. The module supplies 12 volts to the blower motor through the blower motor voltage supply circuit.

Schematic Reference

Connector End View Reference

Description and Operation

  1. «Air Delivery Description and Operation»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual__air-delivery-description-and-operation)
  2. «Air Temperature Description and Operation»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual__air-temperature-description-and-operation)

Electrical Information Reference

  1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition OFF, disconnect the harness X2 connector at the blower motor control module.
  2. Test for less than 1.0 ohm between the ground circuit terminal 5 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 6 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse (HVAC BLWR 40-amp) in the underhood fuse block is open, test all components connected to the B+ circuit and replace as necessary.
  4. Connect a DVOM between the control circuit terminal 3 and the B+ circuit terminal 6.
  5. Cycle the blower motor from OFF to HIGH. The voltage should increase while changing between the commanded states. If voltage remains greater than 11.5 volts while changing between the commanded states, test the control circuit for a short to voltage. If the circuit test normal, replace the HVAC control module. If voltage remains less than 1.0 volts while changing between the commanded states, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC control module. If voltage is between 1.0-11.5 volts and does not increase when changing between the commanded states, replace the HVAC control module.
  6. Ignition OFF, reconnect the harness connector X2 at the blower motor control module. Disconnect the harness connector at the blower motor.
  7. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal A of the blower motor control module and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the blower motor control module.
  8. Connect a test lamp between the control circuit terminal B and the B+ circuit terminal A.
  9. Turn the blower motor on high speed then to low speed. The test lamp intensity should be bright when in high speed and very dim or off when the blower is on low speed. If the test lamp intensity does not vary, test the control circuit for a short to voltage, short to ground, or an open/high resistance. If the circuit tests normal, replace the blower motor control module.
  10. If all circuits test normal, test or replace the blower motor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Blower Motor Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
  2. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for blower motor control module and HVAC control module setup, replacement, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Auxiliary Blower Motor Control Module B+22
Auxiliary Blower Motor B+22
Auxiliary Blower Motor Speed Control221
Auxiliary Blower Motor Control122
Auxiliary Blower Motor Control Module Ground2
1. Auxiliary Blower Motor Always ON 2. Auxiliary Blower Motor Inoperative

The auxiliary blower motor is a variable speed fan. The HVAC control module controls the fan speed by sending a pulse width modulated signal to the auxiliary blower motor control module. The auxiliary blower motor control module varies the duty cycle across the auxiliary blower motor in relation to the pulse width modulated signal. The auxiliary blower motor speed can be adjusted from 10 percent to 90 percent duty cycle (PWM), 90 percent is high speed fan.

Schematic Reference

Connector End View Reference

Description and Operation

  1. «Air Delivery Description and Operation»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual__air-delivery-description-and-operation)
  2. «Air Temperature Description and Operation»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual__air-temperature-description-and-operation)

Electrical Information Reference

  1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, command the auxiliary blower motor ON and OFF with a scan tool. Observe that the auxiliary blower motor turns ON and OFF with each command.

  1. Ignition OFF, disconnect the X2 harness connector at the auxiliary blower motor control module.
  2. Ignition OFF, test for less than 1 ohm between the ground circuit terminal 5 and ground. If greater than the specified range , test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 6 and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
  4. Test for the following voltages between the signal circuit terminal 3 and ground with the auxiliary blower motor speed set at the specified levels: Off-Less than 1 volt Level 1-0.5-8.5 volts Level 2-8.5-9.5 volts Level 3-9.5-10.5 volts Level 4-10.5-11.5 volts If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC control module. If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the HVAC control module.
  5. Reconnect the X2 harness connector at the auxiliary blower motor control module. Disconnect the harness connector at the auxiliary blower motor.
  6. Verify that a test lamp illuminates between the B+ circuit terminal A and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the auxiliary blower motor control module.
  7. Install a test lamp between the B+ circuit terminal A and the control circuit terminal B.
  8. While monitoring the test lamp, cycle the auxiliary blower motor through the various speeds. The test lamp should not illuminate with the auxiliary blower motor in the OFF position and become progressively brighter as the auxiliary blower motor speed is increased. If the test lamp is ON with the auxiliary blower motor in the OFF position, test the control circuit terminal B for a short to ground. If the circuit tests normal, replace the auxiliary blower motor control module. If the test lamp is always OFF, test the control circuit terminal B for a short to voltage or an open/high resistance. If the circuit tests normal, replace the auxiliary blower motor control module. If the test lamp illuminates but does not become progressively brighter as the auxiliary blower motor speed is increased, replace the auxiliary blower motor control module.
  9. If all circuits test normal, test or replace the auxiliary blower motor.

Install a 30A fused jumper wire between the auxiliary blower motor supply voltage terminal A and B+. Momentarily install a jumper wire between the auxiliary blower motor low reference terminal B and ground. The auxiliary blower motor should turn on.

  1. If the function does not perform as specified, replace the auxiliary blower motor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Auxiliary Blower Motor Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
  2. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for auxiliary blower motor control module and HVAC control module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/enclave/i-2007-2013/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Schematic Reference

Connector End View Reference

Description and Operation

  1. «Air Delivery Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)
  2. «Air Temperature Description and Operation»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)

Electrical Information Reference

  1. «Circuit Testing»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/enclave/i-2007-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

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»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic) .
  2. Using the scan tool observe the mode, temperature 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 B0228, B0413, B0423, B0433, B3779, or B3782»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic) .
  3. Engine ON, A/C ON, place the temperature control in the coldest position. Verify that the A/C compressor clutch engages. If the A/C compressor clutch does not engage, refer to «Air Conditioning Compressor Malfunction»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic) . If the A/C compressor is engaged, but air is insufficiently cooled. Refer to «Air Conditioning (A/C) System Performance Test»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__air-conditioning-ac-system-performance-test) .
  4. Turn the A/C OFF and place the temperature control in the warmest position. If the air is insufficiently heated refer to «Heating Performance Diagnostic»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__heating-performance-diagnostic) .
  5. Engine OFF, ignition ON, cover the sunload sensor assembly with a shop towel or other suitable item. Verify the scan tool Right Sunload Sensor and Left Sunload Sensor parameters are within 3 counts of each other. If not within the specified range, refer to Sun Load Sensor Circuit Malfunction.
  6. Measure actual outside air temperature using a thermometer. Compare this value to the scan tool Outside Air Temp. Raw parameter. The measured temperature should be within 5 degrees of parameter. If not within the specified range, refer to Ambient Air Temperature Sensor Circuit Malfunction.
  7. Measure actual inside air temperature using a thermometer. Compare this value to the scan tool Inside Air Temp. Sensor parameter. The measured temperature should be within 5 degrees of parameter. If not within the specified range, refer to Inside Air Temperature Sensor Circuit Malfunction.
  8. Measure actual temperature using a thermometer at each of the duct temperature sensors. Compare this value to the appropriate scan tool Duct Actual parameter. The measured temperature should be within 5 degrees of appropriate Duct Actual parameter. If not within the specified range, refer to Duct Temperature Sensor Circuit Malfunction.
  9. Ignition ON, observe the scan tool A/C Evaporator Temperature Sensor parameter. The reading should be between -39°F (-35°C) and 208°F (98°C) and change with evaporator air temperature changes. If not within the specified range, refer to Evaporator Air Temperature Sensor Circuit Malfunction.

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 C 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 V between the ground circuit terminal C and the appropriate signal circuit terminal listed below: Left solar load sensor circuit terminal A. Right solar load sensor 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 sunload sensor.

Ambient Air Temperature Sensor Circuit Malfunction

  1. Ignition OFF, disconnect the harness connector at the ambient 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 scan tool Outside Air Temp. Raw 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 A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Outside Air Temp. Raw 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 ambient temperature 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 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 scan tool Outside Air Temp. Raw 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 A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Outside Air Temp. Raw 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.

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 A 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 B for a short to ground. If the circuit tests normal, replace the HVAC control module.
  4. Install a 3 A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. 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.

Note. If the evaporator air temperature sensor has an out of range condition caused by a short to voltage, short to ground, or an open/high resistance, the scan tool will display the same value: 11°C (51°F).

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 2 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 V between the signal circuit terminal 1 and low reference 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 evaporator air temperature sensor.
  1. Ignition OFF, disconnect the harness connector at the appropriate temperature sensor.
  2. Test for the appropriate resistance between the signal terminal A or 1 and the low reference terminal B or 2. Refer to «Sensor Resistance Table»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic__sensor-resistance-table) for resistance values.
  1. If not within the specified range, replace the appropriate sensor.

Perform the Diagnostic Repair Verification after completing the repair.

  1. «Duct Air Temperature Sensor Replacement - Upper Right Side»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  2. «Duct Air Temperature Sensor Replacement - Upper Left Side»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  3. «Duct Air Temperature Sensor Replacement - Lower Left Side»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  4. «Duct Air Temperature Sensor Replacement - Lower Right Side»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  5. «Ambient Air Temperature Sensor Replacement (Enclave,Traverse)»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic) , «Ambient Air Temperature Sensor Replacement (Acadia)»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  6. «Evaporator Air Temperature Sensor Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
  7. «Daytime Running Lamp (DRL) Ambient Light Sensor Replacement (Without UV6)»(/buick/enclave/i-2007-2013/remont/exterior-lights/#lighting-system) , «Daytime Running Lamp (DRL) Ambient Light Sensor Replacement (With UV6)»(/buick/enclave/i-2007-2013/remont/exterior-lights/#lighting-system)
  8. «Inside Air Temperature Sensor Aspirator Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
  9. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module replacement, programming and setup

Afterblow Enabling

The afterblow mode can be enabled using the scan tool. The afterblow mode allows the blower motor to operate after the engine has been turned off. This operation of the blower motor dries the evaporator core, which reduces the amount of microbial growth which can create undesirable odors.

Use the following procedure in order to enable the afterblow mode

  1. Connect the Scan Tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Select HVAC Module.
  4. Select HVAC Systems Automatic or Manual.
  5. Select Module Setup.
  6. Select Afterblow Option.
  7. Upon selecting the afterblow option a asterix will appear next to the word afterblow meaning the function is enabled.
  8. Select the save option in the lower left of the screen.

When afterblow has been enabled the blower motor will operate for 2 minutes 30 seconds to 4 minutes after the engine has been in Key OFF for 30 minutes.

The following conditions must be met for the HVAC module to operate the afterblow

  1. The outside air temperature must be at least 21°C (70°F).
  2. The A/C compressor must have operated during the latest key cycle.
  3. The engine must be turned off for at least 30 minutes.
  4. The system voltage must be at least 12 volts.

Actuator Recalibration

When replacing the HVAC control module it will be necessary to allow the HVAC control module to perform a calibration process. When installing the HVAC control module be sure to perform the following

IMPORTANTDo not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.
  1. Place the ignition switch to the OFF position.
  2. Disconnect the scan tool.
  3. Install the HVAC control module.
  4. Connect all previously disconnected components.
  5. Start the vehicle.
  6. Wait 40 seconds for the HVAC control module to self-calibrate.
  7. Verify that no DTCs have set as current DTCs.

When replacing the HVAC actuator it will be necessary to allow the HVAC control module to perform a calibration process. When installing the HVAC actuator be sure to perform one of the following

IMPORTANTDo not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.

Preferred Method (w/Scan Tool)

  1. Clear all DTCs.
  2. Place the ignition switch in the OFF position.
  3. Install the HVAC actuator.
  4. Connect all previously disconnected components.
  5. Start the vehicle.
  6. With the scan tool, initiate the Motor Re-calibration feature of the Heating and Air Conditioning Special Functions menu.
  7. Verify that no DTCs have set as current DTCs.
IMPORTANTDo not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.

Alternate Method (w/o Scan Tool)

  1. Clear all DTCs.
  2. Place the ignition switch to the OFF position.
  3. Install the HVAC actuator.
  4. Connect all previously disconnected components.
  5. Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
  6. Install the HVAC/ECAS fuse.
  7. Start the vehicle.
  8. Wait 40 seconds for the HVAC control module to self-calibrate.
  9. Verify that no DTCs have set as current DTCs.

Scheme 63

Scheme 63: HVAC Control Module Replacement
Scheme 63: HVAC Control Module Replacement
CalloutComponent Name
Preliminary Procedure Remove the instrument panel (I/P) accessory trim plate. Refer to Instrument Panel Accessory Trim Plate Replacement (Acadia) , Instrument Panel Accessory Trim Plate Replacement (Enclave) , Instrument Panel Accessory Trim Plate Replacement (Traverse) .
1HVAC Control Module Screw (Qty: 4) CAUTION: Refer to Fastener Caution . Tighten 2 N.m (18 lb in)
2HVAC Control Module Procedure Reprogram the HVAC Control Module. Refer to Control Module References .
CAUTION
Refer to Fastener Caution .

HVAC Control Module Replacement

Scheme 64

Scheme 64: Auxiliary Heater and Air Conditioning Control Module Replacement
Scheme 64: Auxiliary Heater and Air Conditioning Control Module Replacement
CalloutComponent Name
1Front Floor Console Extension Accessory Upper Bezel Refer to Front Floor Console Extension Accessory Upper Bezel Replacement .
2Front Floor Console Extension Accessory Upper Bezel Screw (Qty: 2) CAUTION: Refer to Fastener Caution . Tighten 2 N.m (18 lb in)
3Front Floor Console Extension Accessory Upper Bezel Closeout
4Auxiliary HVAC Control Module Screw (Qty: 4) CAUTION: Refer to Fastener Caution . Tighten 2 N.m (18 lb in)
5Auxiliary HVAC Control Module Assembly
CAUTION
Refer to Fastener Caution .
CAUTION
Refer to Fastener Caution .

Auxiliary Heater and Air Conditioning Control Module Replacement

Scheme 65

Scheme 65: Air Inlet Valve Actuator Replacement
Scheme 65: Air Inlet Valve Actuator Replacement
CalloutComponent Name
CAUTION: In order to avoid actuator damage, DO NOT apply power to the actuator when it is not installed in the HVAC module. Preliminary Procedures Remove the instrument panel insulator - right side. Refer to Instrument Panel Insulator Panel Replacement - Right Side (Traverse) , Instrument Panel Insulator Panel Replacement - Right Side (Acadia) , Instrument Panel Insulator Panel Replacement - Right Side (Enclave) . Remove the instrument panel (I/P) compartment. Refer to Instrument Panel Compartment Replacement (Acadia) , Instrument Panel Compartment Replacement (Traverse) , Instrument Panel Compartment Replacement (Enclave) .
1Recirculation Actuator Screw (Qty: 3) CAUTION: Refer to Fastener Caution . Tighten 2 N.m (18 lb in)
2Recirculation Actuator Procedure Disconnect the electrical connectors. Re-calibrate the air recirculation actuator. Refer to Actuator Recalibration .
CAUTION
In order to avoid actuator damage, DO NOT apply power to the actuator when it is not installed in the HVAC module.
CAUTION
Refer to Fastener Caution .

Air Inlet Valve Actuator Replacement

Scheme 66

Scheme 66: Mode Valve Actuator Replacement
Scheme 66: Mode Valve Actuator Replacement
CalloutComponent Name
CAUTION: In order to avoid actuator damage, DO NOT apply power to the actuator when it is not installed in the HVAC module. Preliminary Procedures Remove the instrument panel insulator - right side. Refer to Instrument Panel Insulator Panel Replacement - Right Side (Traverse) , Instrument Panel Insulator Panel Replacement - Right Side (Acadia) , Instrument Panel Insulator Panel Replacement - Right Side (Enclave) . Remove the instrument panel (I/P) compartment. Refer to Instrument Panel Compartment Replacement (Acadia) , Instrument Panel Compartment Replacement (Traverse) , Instrument Panel Compartment Replacement (Enclave) .
1Mode Actuator Screw (Qty: 3) CAUTION: Refer to Fastener Caution . Tighten 2 N.m (18 lb in)
2Mode Actuator Procedure Disconnect the electrical connectors. Re-calibrate the right temperature actuator. Refer to Actuator Recalibration .
CAUTION
In order to avoid actuator damage, DO NOT apply power to the actuator when it is not installed in the HVAC module.
CAUTION
Refer to Fastener Caution .

Mode Valve Actuator Replacement

Scheme 67

Scheme 67: Temperature Valve Actuator Replacement - Right Side
Scheme 67: Temperature Valve Actuator Replacement - Right Side
CalloutComponent Name
CAUTION: In order to avoid actuator damage, DO NOT apply power to the actuator when it is not installed in the HVAC module. Preliminary Procedures Remove the front floor console extension panel. Refer to Front Floor Console Extension Panel Replacement - Right Side (Enclave) , Front Floor Console Extension Panel Replacement - Right Side (Traverse) , Front Floor Console Extension Panel Replacement - Right Side (Acadia) Remove the instrument panel insulator - right side. Refer to Instrument Panel Insulator Panel Replacement - Right Side (Traverse) , Instrument Panel Insulator Panel Replacement - Right Side (Acadia) , Instrument Panel Insulator Panel Replacement - Right Side (Enclave) . Remove the instrument panel (I/P) compartment. Refer to Instrument Panel Compartment Replacement (Acadia) , Instrument Panel Compartment Replacement (Traverse) , Instrument Panel Compartment Replacement (Enclave) .
1Right Temperature Actuator Screw (Qty: 3) CAUTION: Refer to Fastener Caution . Tighten 2 N.m (18 lb in)
2Right Temperature Actuator Procedure Disconnect the electrical connectors. Re-calibrate the right temperature actuator. Refer to Actuator Recalibration .
CAUTION
In order to avoid actuator damage, DO NOT apply power to the actuator when it is not installed in the HVAC module.
CAUTION
Refer to Fastener Caution .

Temperature Valve Actuator Replacement - Right Side

Scheme 68

Scheme 68: Temperature Valve Actuator Replacement - Left Side
Scheme 68: Temperature Valve Actuator Replacement - Left Side
CalloutComponent Name
CAUTION: In order to avoid actuator damage, DO NOT apply power to the actuator when it is not installed in the HVAC module. Preliminary Procedure Remove the instrument panel insulator - left side. Refer to Instrument Panel Insulator Panel Replacement - Left Side (Enclave) , Instrument Panel Insulator Panel Replacement - Left Side (Acadia) , Instrument Panel Insulator Panel Replacement - Left Side (Traverse) .
1Left Temperature Actuator Screw (Qty: 3) CAUTION: Refer to Fastener Caution . Tighten 2 N.m (18 lb in)
2Left Temperature Actuator Procedure Disconnect the electrical connectors. Re-calibrate the right temperature actuator. Refer to Actuator Recalibration .
CAUTION
In order to avoid actuator damage, DO NOT apply power to the actuator when it is not installed in the HVAC module.
CAUTION
Refer to Fastener Caution .

Temperature Valve Actuator Replacement - Left Side

Scheme 69

Scheme 69: Auxiliary Temperature Valve Actuator Replacement
Scheme 69: Auxiliary Temperature Valve Actuator Replacement
CalloutComponent Name
CAUTION: In order to avoid actuator damage, DO NOT apply power to the actuator when it is not installed in the HVAC module. Preliminary Procedures Remove the rear quarter lower trim panel. Refer to Quarter Lower Rear Trim Panel Replacement (Acadia with TB5) , Quarter Lower Rear Trim Panel Replacement (Traverse with TB5) , Quarter Lower Rear Trim Panel Replacement (Traverse with TB4) , Quarter Lower Rear Trim Panel Replacement (Enclave with TB5) , Quarter Lower Rear Trim Panel Replacement (Acadia with TB4) , Quarter Lower Rear Trim Panel Replacement (Enclave with TB4) . Remove the rear wheelhouse liner panel. Refer to Rear Wheelhouse Panel Liner Replacement . Remove the HVAC module mounting nuts and reposition the auxiliary HVAC module inward to gain access to the temp door actuator. Disconnect the electrical connector from the temp actuator (2).
1Temp Door Actuator Screw (Qty: 2) CAUTION: Refer to Fastener Caution . Tighten 2.5 N.m (16 lb in)
2Auxiliary Temp Door Actuator Procedure Re-calibrate the air temp actuator. Refer to Actuator Recalibration .
CAUTION
In order to avoid actuator damage, DO NOT apply power to the actuator when it is not installed in the HVAC module.
CAUTION
Refer to Fastener Caution .

Auxiliary Temperature Valve Actuator Replacement

Scheme 70

Scheme 70: Auxiliary Mode Valve Actuator Replacement
Scheme 70: Auxiliary Mode Valve Actuator Replacement
CalloutComponent Name
CAUTION: In order to avoid actuator damage, DO NOT apply power to the actuator when it is not installed in the HVAC module. Preliminary Procedures Remove the right rear quarter trim panel. Refer to Quarter Lower Rear Trim Panel Replacement (Acadia with TB5) , Quarter Lower Rear Trim Panel Replacement (Traverse with TB5) , Quarter Lower Rear Trim Panel Replacement (Traverse with TB4) , Quarter Lower Rear Trim Panel Replacement (Enclave with TB5) , Quarter Lower Rear Trim Panel Replacement (Acadia with TB4) , Quarter Lower Rear Trim Panel Replacement (Enclave with TB4) . Remove the rear wheelhouse liner panel. Refer to Rear Wheelhouse Panel Liner Replacement . Remove the HVAC module mounting nuts and reposition the auxiliary HVAC module inward to gain access to the mode door actuator. Disconnect the electrical connector from the mix door actuator.
1Mode Door Actuator Screw (Qty: 2) CAUTION: Refer to Fastener Caution . Tighten 2.5 N.m (16 lb in)
2Auxiliary Mode Door Actuator Procedure Re-calibrate the mode actuator. Refer to Actuator Recalibration .
CAUTION
In order to avoid actuator damage, DO NOT apply power to the actuator when it is not installed in the HVAC module.
CAUTION
Refer to Fastener Caution .

Auxiliary Mode Valve Actuator Replacement

Scheme 71

Scheme 71: Inside Air Temperature Sensor Aspirator Replacement
Scheme 71: Inside Air Temperature Sensor Aspirator Replacement
CalloutComponent Name
Preliminary Procedure Remove the driver knee bolster. Refer to Driver Knee Bolster Replacement (Acadia) , Driver Knee Bolster Replacement (Traverse) , Driver Knee Bolster Replacement (Enclave) .
1Aspirator Assembly Procedure Disconnect the electrical connector. Rotate the aspirator to remove from inlet hose.

Inside Air Temperature Sensor Aspirator Replacement

Scheme 72

Scheme 72: Duct Air Temperature Sensor Replacement - Upper Right Side
Scheme 72: Duct Air Temperature Sensor Replacement - Upper Right Side
CalloutComponent Name
Preliminary Procedure Remove the I/P compartment. Refer to Instrument Panel Compartment Replacement (Acadia) , Instrument Panel Compartment Replacement (Traverse) , Instrument Panel Compartment Replacement (Enclave) .
1Air Temperature Sensor- Upper Right Procedure Disconnect the electrical connector. Grasp and pull sensor straight downward from air duct.

Duct Air Temperature Sensor Replacement - Upper Right Side

Scheme 73

Scheme 73: Duct Air Temperature Sensor Replacement - Upper Left Side
Scheme 73: Duct Air Temperature Sensor Replacement - Upper Left Side
CalloutComponent Name
Preliminary Procedure Remove the driver knee bolster. Refer to Driver Knee Bolster Replacement (Acadia) , Driver Knee Bolster Replacement (Traverse) , Driver Knee Bolster Replacement (Enclave) .
1Air Temperature Sensor- Upper Left Procedure Disconnect the electrical connector. Grasp and pull sensor straight downward from air duct.

Duct Air Temperature Sensor Replacement - Upper Left Side

Scheme 74

Scheme 74: Duct Air Temperature Sensor Replacement - Lower Left Side
Scheme 74: Duct Air Temperature Sensor Replacement - Lower Left Side
CalloutComponent Name
Preliminary Procedure Remove the front floor console extension panel- left side. Refer to Front Floor Console Extension Panel Replacement - Left Side (Enclave) , Front Floor Console Extension Panel Replacement - Left Side (Traverse) , Front Floor Console Extension Panel Replacement - Left Side (Acadia) .
1Air Temperature Sensor- Lower Left Procedure Disconnect the electrical connector. Grasp and pull sensor straight outward from HVAC case.

Duct Air Temperature Sensor Replacement - Lower Left Side

Scheme 75

Scheme 75: Duct Air Temperature Sensor Replacement - Lower Right Side
Scheme 75: Duct Air Temperature Sensor Replacement - Lower Right Side
CalloutComponent Name
Preliminary Procedure Remove the front floor console extension panel- right side. Refer to Front Floor Console Extension Panel Replacement - Right Side (Enclave) , Front Floor Console Extension Panel Replacement - Right Side (Traverse) , Front Floor Console Extension Panel Replacement - Right Side (Acadia) . Remove the instrument panel insulator- right side. Refer to Instrument Panel Insulator Panel Replacement - Right Side (Traverse) , Instrument Panel Insulator Panel Replacement - Right Side (Acadia) , Instrument Panel Insulator Panel Replacement - Right Side (Enclave) .
1Air Temperature Sensor- Lower Right Procedure Disconnect the electrical connector. Grasp and pull sensor straight outward from HVAC case.

Duct Air Temperature Sensor Replacement - Lower Right Side

Scheme 76

Scheme 76: Ambient Air Temperature Sensor Replacement (Enclave,Traverse)
Scheme 76: Ambient Air Temperature Sensor Replacement (Enclave,Traverse)
CalloutComponent Name
Preliminary Procedure Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle
1Ambient Air Sensor Procedure Disconnect the ambient air sensor harness connector. Rotate the sensor counter clockwise in order to remove the sensor from the bracket.

Ambient Air Temperature Sensor Replacement (Enclave,Traverse)

Scheme 77

Scheme 77: Ambient Air Temperature Sensor Replacement (Acadia)
Scheme 77: Ambient Air Temperature Sensor Replacement (Acadia)
CalloutComponent Name
Preliminary Procedure Remove the front radiator grill. Refer to Radiator Grille Replacement (Acadia)
1Ambient Air Temperature Sensor Procedure Disconnect the ambient air sensor harness connector. Rotate the sensor counter clockwise in order to remove the sensor from the bracket.

Ambient Air Temperature Sensor Replacement (Acadia)

Air Delivery Description and Operation

The air delivery description and operation is divided into 7 areas

  1. HVAC Control Components
  2. Air Speed
  3. Auxiliary Air Speed
  4. Air Delivery
  5. Auxiliary Air Delivery
  6. Recirculation Operation
  7. Automatic Operation

HVAC Control Components

HVAC Control Module

The HVAC control module is a GMLAN device that interfaces between the Operator and the HVAC system to maintain air temperature and distribution settings. The battery positive voltage circuit provides power that the control module uses for keep alive memory (KAM). If the battery positive voltage circuit loses power, all HVAC DTCs and settings will be erased from KAM. The body control module (BCM), which is the vehicle mode master, provides a device on signal. The control module supports the following features

FeatureAvailability
AfterblowYes
PurgeNo
PersonalizationNO
Actuator CalibrationYes

Auxiliary HVAC Control Module (without RSA)

The Auxiliary HVAC Control Module uses a set of three potentiometers to control rear fan speed, temperature, and mode settings. The Auxiliary HVAC Control module has inputs for 5V and low Reference that is used by all three potentiometers. There are three signal circuits between each of the potentiometers and the HVAC Control Module.

Auxiliary HVAC Control Module (with RSA)

Auxiliary HVAC Control functions are integrated into the Rear Seat Entertainment Module. The Rear Seat Entertainment Module communicates Rear HVAC settings over serial data.

Auxiliary HVAC Control Functions

All Auxiliary functions and DTCs are handled by the HVAC control module. There are two ways the rear functions can be controlled.

Control from the HVAC control module: If the AUX button on the HVAC control module is pressed, the rear HVAC system will be enabled. The settings for the rear will mimic the Driver settings on the HVAC Control Module.

Control from the auxiliary HVAC control module: If at any time any of the three Auxiliary controls are adjusted, control of the rear HVAC System will transfer to the Auxiliary controls. If the Aux button is not currently enabled, adjusting the Auxiliary controls will enable it, even if the front system is Off.

Auxiliary Mode Actuator

The auxiliary Mode actuator is a 5-wire bi-directional electric motor that incorporates a feedback potentiometer. Low reference, 5-volt reference, position signal, and 2 control circuits enable the actuator to operate. The control circuits use either a 0 or 12-volt value to coordinate the actuator movement. When the actuator is at rest, both control circuits have a value of 0 volts. In order to move the actuator, the HVAC control module grounds one of the control circuits while providing the other with 12 volts. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction. When the actuator shaft rotates, the potentiometers adjustable contact changes the door position signal between 0-5 volts. The HVAC control module uses a range of 0-255 counts to index the actuator position. The door position signal voltage is converted to a 0-255 count range. When the module sets a commanded, or targeted value, one of the control circuits is grounded. As the actuator shaft rotates the changing position signal is sent to the module. Once the position signal and the commanded value are the same, the module removes power and ground from the control circuits.

The auxiliary HVAC control module uses a range of 0-255 counts to index the actuator position. The door position signal voltage is converted to a 0-255 count range. When the module sets a commanded, or targeted, value, the control signal is changed to either 0 or 5 volts depending upon the direction that the actuator needs to rotate to reach the commanded value. As the actuator shaft rotates the changing position signal is sent to the module.

Once the position signal and the commanded value are the same, the module changes the control signal to 2.5 volts.

Blower Motor Control Processor

The blower motor control processor controls the speed of the blower motor by increasing or decreasing the voltage drop on the ground side of the blower motor. The HVAC control module provides a low side pulse width modulated signal to the blower motor control processor over the blower motor speed control circuit. As the requested blower speed increases, the HVAC control module increases the amount of time that the speed signal is modulated to ground. As the requested blower speed decreases, the HVAC control module decreases the amount of time that the signal is modulated to ground.

Auxiliary Blower Motor Control Processor

The auxiliary blower motor control processor controls the speed of the blower motor by increasing or decreasing the voltage drop on the ground side of the auxiliary blower motor. The auxiliary HVAC control module provides a low side pulse width modulated signal to the auxiliary blower motor control processor over the auxiliary blower motor speed control circuit. As the requested blower speed increases, the auxiliary HVAC control module increases the amount of time that the speed signal is modulated to ground. As the requested blower speed decreases, the auxiliary HVAC control module decreases the amount of time that the signal is modulated to ground.

Air Speed - Front Control

The blower control switch is integrated into the HVAC control module. The 2 rocker type switches provide the vehicle operator the ability to select several blower speeds. The HVAC control module uses a bar graph type display to indicate the selected blower speed. The blower motor control processor supplies a 5-volt reference to the HVAC control module on the blower motor speed control circuit. The HVAC control module pulls the 5 volts reference low towards ground to provide a blower motor speed signal. As the voltage decreases the blower speed increases. Power and ground are provided to the blower motor control processor through the battery positive voltage and ground circuits. When the HVAC control module is operating in AUTO mode, the system automatically controls the blower speed. If an OnStar® call is initiated while the blower is in the high speed position the blower speed will be lowered to reduce background noise.

Air Speed - Auxiliary

There are 2 separate operator controls for the auxiliary HVAC system. There is the front auxiliary HVAC control assembly and the rear seat audio (RSA) control module. If the front auxiliary blower motor switch is in the AUX. position, then the system will only function with inputs to the front auxiliary HVAC control assembly. If the front auxiliary blower motor switch is in the OFF position, then the RSA control module does not respond to input. The auxiliary HVAC control module can not request A/C operation from the PCM. A rocker type switch on the RSA control module provides the operator the ability to select several blower speeds. The RSA control module uses a bar graph to indicate the selected blower speed. The auxiliary blower motor control processor supplies a 5-volt reference to the auxiliary HVAC control module on the auxiliary blower motor speed control circuit. The auxiliary HVAC control module pulls the 5-volt reference low towards ground to provide a blower motor speed signal. As the voltage decreases the blower speed increases. Power and ground are provided to the auxiliary blower motor control processor through the battery positive voltage and ground circuits.

Afterblow

Afterblow is a feature that dries the evaporator core by operating the blower motor after the engine is turned off. This reduces the amount of microbial growth that can create undesirable odors. The vehicle does not come equipped with the afterblow feature turned on. If the afterblow feature is required due to an odor concern, it must be turned on by the scan tool.

The following conditions must be met for afterblow to operate

  1. The A/C compressor operated during the prior key cycle.
  2. The system voltage is at least 11 volts to start and 10 volts to continue to run.
  3. The ignition has been in the OFF position for at least 30 minutes.

Once the above conditions have been met the following sequence of events will occur

  1. The blower will run for a range of 2 minutes 30 seconds to 4 minutes.
  2. The recirculation door moves to outside air position.
  3. The mode valve moves to the floor position.

Air Distribution

The HVAC control module controls the distribution of air by the use of a mode actuator. The modes that may be selected are

  1. Defrost
  2. Defog
  3. Panel
  4. BI-Level
  5. Floor

The mode actuator is connected to the mode door by a cam type linkage system. Depending on the position of the door, air is directed through the HVAC module and distributed through various ducts leading to the outlets in the dash. If the HVAC control module detects a fault with the mode door the HVAC control module will try to drive the actuator for a predetermined amount of time, to defrost, which is the defaulted position for the mode door actuator. When the mode switch is placed in the defrost or defog positions the A/C is commanded on and the recirculation door is moved to the outside air position to help reduce window fogging. A/C is available in all modes and recirculation is only available in the panel and bi-level modes.

Mode Actuator

The Mode actuator is a 5-wire bi-directional electric motor that incorporates a feedback potentiometer. Low reference, 5-volt reference, position signal, and 2 control circuits enable the actuator to operate. The control circuits use either a 0 or 12-volt value to coordinate the actuator movement. When the actuator is at rest, both control circuits have a value of 0 volts. In order to move the actuator, the HVAC control module grounds one of the control circuits while providing the other with 12 volts. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction. When the actuator shaft rotates, the potentiometers adjustable contact changes the door position signal between 0-5 volts. The HVAC control module uses a range of 0-255 counts to index the actuator position. The door position signal voltage is converted to a 0-255 count range. When the module sets a commanded, or targeted value, one of the control circuits is grounded. As the actuator shaft rotates the changing position signal is sent to the module. Once the position signal and the commanded value are the same, the module removes power and ground from the control circuits.

Front Defrost

When defrost is selected, the A/C compressor is activated. The A/C compressor clutch will engage when ambient temperatures are above 3°C (38°F). The blower motor will be activated, regardless of the coolant temperature. The HVAC control module will override the auxiliary HVAC control module so a high volume of air is delivered to the front defrost vents. The rear window defogger does not affect the HVAC system.

Air Distribution - Auxiliary Control

The auxiliary HVAC system provides ventilation for the rear seat occupants. The rear seat occupants will exercise control of the auxiliary air delivery modes, air speed and air temperature setting.

When the auxiliary mode switch is toggled, a signal is sent to the auxiliary mode actuator through the auxiliary mode door control circuit. Power and ground are supplied to the auxiliary mode actuator through the ignition 3 voltage and ground circuits.

When the HVAC control module is ON, the air that is delivered to the auxiliary HVAC system is the low auxiliary blower speed. When the operator selects medium blower speed, power is delivered to the auxiliary blower motor through the auxiliary blower motor medium speed control circuit.

When the operator selects high blower speed, power is delivered to the auxiliary blower motor through the auxiliary blower motor high speed control circuit. Ground is provided to the blower motor through the ground circuit. Power and ground are provided to the auxiliary HVAC control module through the ignition 3 voltage and ground circuits.

Recirculation Operation

The HVAC control module controls the air intake through the recirculation actuator. The recirculation switch closes the recirculation door in order to circulate the air within the vehicle. The outside air switch opens the recirculation door in order to route outside air into the vehicle. Regardless of the blower motor switch position, recirculation is available only in the panel and bi-level mode switch positions. Including the OFF position. The mode switch must be placed in either the panel or bi-level position before the blower motor switch is placed in the OFF position. In order to reduce windshield fogging, outside air is circulated when the mode switch is in the defrost or defog positions. If the recirculation switch is pressed into the ON position when the mode switch is in an unavailable mode position, then the recirculation switch LED will flash 3 times. If the HVAC control module detects a fault with the recirc door the HVAC control module will try to drive the actuator for a predetermined amount of time, to outside air, which is the defaulted position for the recirculation actuator.

Automatic Operation

In automatic operation, the HVAC control module will maintain the comfort level inside of the vehicle by controlling the A/C compressor clutch, the blower motor, the air temperature actuators, mode actuator and circulation.

To place the HVAC system in Automatic mode, the following is required

  1. The Auto switch must be activated
  2. The air temperature switch must be in any other position other than full hot or full cold position

Once the desired temperature is reached, the blower motor, mode, recirculation and temperature actuators will automatically be adjusted to maintain the temperature selected. The HVAC control module performs the following functions to maintain the desired air temperature

  1. Monitor the following sensors: Inside air temperature sensor Ambient Air Temperature Sensor Lower Left Air Temperature Sensor Lower Right Air Temperature Sensor Upper Left Air Temperature Sensor Upper Right Air Temperature Sensor
  2. Regulate blower motor speed
  3. Position the air temperature actuator
  4. Position the mode actuator
  5. Position the recirculation actuator
  6. Request A/C operation

Air Temperature Description and Operation

The air temperature controls are divided into 7 areas

  1. HVAC Control Components
  2. Heating and A/C Operation
  3. Auxiliary Heating and A/C Operation
  4. Automatic Operation
  5. Auxiliary Automatic Operation
  6. Engine Coolant
  7. A/C Cycle

The HVAC control module is a GMLAN device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The battery positive voltage circuit provides power that the control module uses for keep alive memory (KAM). If the battery positive voltage circuit loses power, all HVAC DTCs and settings will be erased from KAM. The body control module (BCM), which is the vehicle mode master, provides a device on signal. The control module supports the following features

FeatureAvailability
AfterblowYes
PurgeNo
PersonalizationNo
Actuator CalibrationYes

Auxiliary HVAC Control Module (without RSA)

The Auxiliary HVAC Control Module uses a set of three potentiometers to control rear fan speed, temperature, and mode settings. The Auxiliary HVAC Control module has inputs for 5V and low Reference that is used by all three potentiometers. There are three signal circuits between each of the potentiometers and the HVAC Control Module.

Auxiliary HVAC Control Module (with RSA)

Auxiliary HVAC Control functions are integrated into the Rear Seat Entertainment Module. The Rear Seat Entertainment Module communicates Rear HVAC settings over serial data.

Auxiliary HVAC Control Functions

All Auxiliary functions and DTCs are handled by the HVAC control module. There are two ways the rear functions can be controlled.

Control from the HVAC control module: If the AUX button on the HVAC control module is pressed, the rear HVAC system will be enabled. The settings for the rear will mimic the Driver settings on the HVAC Control Module.

Control from the auxiliary HVAC control module: If at any time any of the three Auxiliary controls are adjusted, control of the rear HVAC System will transfer to the Auxiliary controls. If the Aux button is not currently enabled, adjusting the Auxiliary controls will enable it, even if the front system is Off.

Air Temperature Actuators

The air temperature actuator is a 5-wire bi-directional electric motor that incorporates a feedback potentiometer. Low reference, 5-volt reference, position signal, and 2 control circuits enable the actuator to operate. The driver air temperature actuator is a reverse polarity motor. The control circuits use either a 0 or 12-volt value to coordinate the actuator movement. When the actuator is at rest, both control circuits have a value of 0 volts. In order to move the actuator, the HVAC control module grounds one of the control circuits while providing the other with 12 volts. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction. When the actuator shaft rotates, the potentiometers adjustable contact changes the door position signal between 0-5 volts. The HVAC control module uses a range of 0-255 counts to index the actuator position. The door position signal voltage is converted to a 0-255 count range. When the module sets a commanded, or targeted value, one of the control circuits is grounded. As the actuator shaft rotates the changing position signal is sent to the module. Once the position signal and the commanded value are the same, the module removes power and ground from the control circuits.

Auxiliary Air Temperature Actuator

The auxiliary air temperature actuator is a 5-wire bi-directional electric motor that incorporates a feedback potentiometer. Low reference, 5-volt reference, position signal, and 2 control circuits enable the actuator to operate. The driver air temperature actuator is a reverse polarity motor. The control circuits use either a 0 or 12-volt value to coordinate the actuator movement. When the actuator is at rest, both control circuits have a value of 0 volts. In order to move the actuator, the HVAC control module grounds one of the control circuits while providing the other with 12 volts. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction. When the actuator shaft rotates, the potentiometers adjustable contact changes the door position signal between 0-5 volts. The HVAC control module uses a range of 0-255 counts to index the actuator position. The door position signal voltage is converted to a 0-255 count range. When the module sets a commanded, or targeted value, one of the control circuits is grounded. As the actuator shaft rotates the changing position signal is sent to the module. Once the position signal and the commanded value are the same, the module removes power and ground from the control circuits.

Air Temperature Sensor

The air temperature sensors are a 2-wire negative temperature co-efficient thermistor. The vehicle uses the following air temperature sensors

  1. Ambient Air Temperature Sensor
  2. Inside Air Temperature Sensor Assembly
  3. Upper Left Air Temperature Sensor
  4. Upper Right Air Temperature Sensor
  5. Lower Left Air Temperature Sensor
  6. Lower Right Air Temperature Sensor

A signal and low reference circuit enables the sensor to operate. As the air temperature surrounding the sensor increases, the sensor resistance decreases. The sensor signal voltage decreases as the resistance decreases. The sensor operates within a temperature range between -40 to +101°C (-40 to +215°F). The sensor signal varies between 0-5 volts.

The input of the duct air temperature sensors are different from the ambient and inside air temperature sensors. The HVAC control module converts the signal to a range between 0-255 counts. As the air temperature increases the count value will decrease. If the HVAC control module or auxiliary HVAC control module detects a malfunctioning sensor, then the control module software will use a defaulted air temperature value. The default value for the ambient and inside air temperature sensors will be displayed on the scan tool. The default value for the duct air temperature sensors will not be displayed on the scan tool. The scan tool parameter for the duct air temperature sensors are the actual state of the signal circuit. The default action ensures that the HVAC system can adjust the inside air temperature near the desired temperature until the condition is corrected.

Ambient Air Temperature Sensor

The ambient air temperature sensor mounts underhood and can be affected by city traffic, by idling, and by restarting a hot engine. Therefore, the HVAC control module filters the value of the ambient air temperature sensor for temperature display. If the ambient air temperature sensor drops below 2°C (35°F) the compressor clutch will be disabled until the ignition is OFF for more than 3 hours or an instant OAT update is performed no matter what the actual temperature is due to the filtered value being used by the HVAC control module. The ambient air temperature value is updated under the following conditions

ConditionDisplay
Using Scan Tool Special FunctionUpdates temperature display instantly
When the HVAC module RECIRC, and A/C buttons are pressed simultaneously.Updates temperature display instantly
At start up with the engine off less than 3 hoursDisplays last stored temperature unless temperature has decreased. The outside air temperature reading is always instantly updated if ambient air temperature has decreased.
At start up with the engine off more than 3 hoursDisplays actual outside temperature
Vehicle speed above 32 km/h (20 mph) for a minimum of 80 secondsUpdates temperature display at a slow filtered rate
Vehicle speed above 72 km/h (45 mph)Displays actual outside temperature
Sensor ambient temperature reading is less than the last displayed valueDisplays actual outside temperature
When the ambient air decreases.Updates temperature display rapidly

Sunload Sensor Assembly

The sunload sensor is a 2-wire photo diode. The vehicle uses left and right sunload sensors. The 2 sensors are integrated into the sunload sensor assembly. Low reference and signal circuits enable the sensor to operate. As the light shining upon the sensor gets brighter, the sensor resistance increases. The sensor signal decreases as the resistance increases. The sensor operates within an intensity range between completely dark and bright. The sensor signal varies between 0-5 volts. The HVAC control module converts the signal to a range between 0-255 counts. The sunload sensor provides the HVAC control module a measurement of the amount of light shining on the vehicle. Bright, or high intensity, light causes the vehicles inside temperature to increase. The HVAC system compensates for the increased temperature by diverting additional cool air into the vehicle. If the HVAC control module detects a malfunctioning sensor, then the control module software will use a defaulted sunload value. This value will not be displayed on the scan tool. The default action ensures that the HVAC system can adjust the inside air temperature near the desired temperature until the condition is fixed. The scan tool parameter for the sunload sensor is the actual state of the signal circuit.

Evaporator Temperature Sensor

The evaporator temperature sensor is a 2-wire negative temperature co-efficient thermistor. The sensor operates within a temperature range of -40 to +85°C (-40 to +185°F). The sensor is installed at the evaporator and measures its temperature. If the temperature drops under 3°C (38°F), the compressor will be switched off in order to prevent a frozen evaporator.

A/C Refrigerant Pressure Sensor

The A/C refrigerant pressure sensor is a 3-wire piezoelectric pressure transducer. A 5-volt reference, low reference, and signal circuits enable the sensor to operate. The A/C pressure signal can be between 0-5 volts. When the A/C refrigerant pressure is low, the signal value is near 0 volts. When the A/C refrigerant pressure is high, the signal value is near 5 volts. The powertrain control module (PCM) converts the voltage signal to a pressure value.

The A/C refrigerant pressure sensor protects the A/C system from operating when an excessively high pressure condition exists. The PCM disables the compressor clutch if the A/C pressure is more than 2957 kPa (429 psi). The clutch will be enabled after the pressure decreases to less than 1578 kPa (229 psi).

Heating and A/C Operation

The purpose of the heating and A/C system is to provide heated and cooled air to the interior of the vehicle. The A/C system will also remove humidity from the interior and reduce windshield fogging. The vehicle operator can determine the passenger compartment temperature by adjusting the air temperature switch. The vehicle passenger can offset the passenger temperature as much as 16.7°C (30°F). Regardless of the temperature setting, the following can effect the rate that the HVAC system can achieve the desired temperature

  1. Recirculation actuator setting
  2. Difference between inside and desired temperature
  3. Difference between ambient and desired temperature
  4. Blower motor speed setting
  5. Mode setting
  6. Auxiliary HVAC settings

The control module makes the following actions when automatic operation is not selected, and an air temperature setting is selected

When the air temperature switch is placed in the warmest position, the control module commands the air temperature door to divert maximum air past the heater core.

When the air temperature switch is placed in the coldest position, the control module commands the air temperature door to direct air to bypass the heater core.

When the air temperature switch is placed between the warmest and coldest positions, the control module monitors the following sensor inputs to determine the air temperature door position that diverts the appropriate amount of air past the heater core in order to achieve the desired temperature

  1. Sunload
  2. Duct temperatures
  3. Ambient temperature
  4. Inside temperature

The A/C system can be engaged by either pressing the A/C switch or during automatic operation. The HVAC control module sends a GMLAN message to the PCM for A/C compressor engagement. The PCM will provide a ground for the A/C compressor relay enabling it to close its internal contacts to send battery voltage to the A/C compressor clutch coil. The A/C compressor diode will prevent a voltage spike, resulting from the collapse of the magnetic field of the coil, from entering the vehicle electrical system when the compressor is disengaged.

The following conditions must be met in order for the A/C compressor clutch to turn on

  1. Ambient air temperature above 2°C (35°F)
  2. A/C low pressure switch signal circuit is grounded
  3. A/C refrigerant pressure sensor parameter is less than 2957 kPa (429 psi)
  4. PCM receives an A/C request from the HVAC control module
  5. Engine coolant temperature (ECT) is less than 121°C (250°F)
  6. The engine RPM is more than 550 RPM
  7. The throttle position is less than 100 percent

The HVAC control module monitors the A/C low pressure switch signal circuit. If the voltage signal on this circuit has no voltage drop the module will interpret this condition as a low pressure, disabling the A/C request. The A/C low pressure switch will open its internal contacts at 151 kPa (22 psi). Then close the contacts at 275 kPa (40 psi) to resume A/C operation. This switch assists in cycling the A/C compressor and prevents A/C compressor operation if system has a low refrigerant level.

The PCM monitors the A/C refrigerant pressure sensor signal circuit. The voltage signal on this circuit is proportional to the refrigerant pressure inside the A/C high side pressure line. As the pressure inside the line increases, so does the voltage signal. If the pressure is above 2957 kPa (429 psi), the A/C compressor output is disabled. When the pressure lowers to 1578 kPa (229 psi), the PCM enables the compressor to operate.

The sensor information is used by the PCM to determine the following

  1. The A/C high side pressure
  2. An A/C system load on the engine
  3. An excessive A/C high side pressure
  4. The heat load at the A/C condenser

Once engaged, the compressor clutch will be disengaged for the following conditions

  1. Ambient air temperature is less than 4°C (39°F)
  2. Throttle position is 100 percent
  3. The A/C low pressure switch is open
  4. A/C high side pressure is more than 2957 kPa (429 psi)
  5. A/C low side pressure is less than 151 kPa (22 psi)
  6. Engine coolant temperature (ECT) is more than 121°C (250°F)
  7. Engine speed is more than 5500 RPM
  8. Transmission shift
  9. PCM detects excessive torque load
  10. PCM detects insufficient idle quality
  11. PCM detects a hard launch condition

In automatic operation, the HVAC control module will maintain the comfort level inside of the vehicle by controlling the A/C compressor clutch, the blower motor, the air temperature actuators, mode actuator and recirculation.

To place the HVAC system in Automatic mode, the following is required

The Auto switch must be activated The air temperature switch must be in any other position other than full hot or full cold position

Once the desired temperature is reached, the blower motor, mode, recirculation and temperature actuators will automatically be adjusted to maintain the temperature selected. The HVAC control module performs the following functions to maintain the desired air temperature

  1. Monitor the following sensors: Inside Air Temperature Sensor Ambient Air Temperature Sensor Lower Left Air Temperature Sensor Lower Right Air Temperature Sensor Upper Left Air Temperature Sensor Upper Right Air Temperature Sensor
  2. Regulate blower motor speed
  3. Position the air temperature actuator
  4. Position the mode actuator
  5. Position the recirculation actuator
  6. Request A/C operation

In automatic operation, the auxiliary HVAC control module will maintain the comfort level inside of the vehicle by controlling the auxiliary blower motor, the auxiliary air temperature actuator and the auxiliary mode actuator.

To place the auxiliary HVAC system in Automatic mode, the following is required

  1. The auxiliary blower motor switch on the front HVAC control assembly must be in the Auto position.
  2. The auxiliary mode switch on the front HVAC control assembly must be in the Auto position.
  3. The auxiliary air temperature switch must be in any other position other than full hot or full cold position.

Once the desired temperature is reached, the auxiliary blower motor, auxiliary mode and auxiliary temperature actuator will automatically be adjusted to maintain the temperature selected. The auxiliary HVAC control module performs the following functions to maintain the desired air temperature

  1. Upper Air Temperature Sensor - Auxiliary
  2. Lower Air Temperature Sensor - Auxiliary
  3. Regulate auxiliary blower motor speed
  4. Position the auxiliary air temperature actuator
  5. Position the auxiliary mode actuator

Engine Coolant

Engine coolant is the essential element of the heating system. The thermostat controls the normal engine operating coolant temperature. The thermostat also creates a restriction for the cooling system that promotes a positive coolant flow and helps prevent cavitation. Coolant enters the heater core through the inlet heater hose, in a pressurized state. The heater core is located inside the HVAC module. The ambient air drawn through the HVAC module absorbs the heat of the coolant flowing through the heater core. Heated air is distributed to the passenger compartment, through the HVAC module, for passenger comfort. Opening or closing the air temperature door controls the amount of heat delivered to the passenger compartment. The coolant exits the heater core through the return heater hose and recirculated back through the engine cooling system.

Special Tools

Illustration Tool Number/ Description J 43600 ACR 2000 Air Conditioning Service Center

Scheme 78

Scheme 78: Special Tools
Scheme 78: Special Tools

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• COMPONENT CONNECTOR END VIEWS - INDEX
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Control Module References
• Diagnostic Repair Verification
• Daytime Running Lamp (DRL) Ambient Light Sensor Replacement (Without UV6)
• HVAC Schematics
• Evaporator Air Temperature Sensor Replacement
• Air Conditioning (A/C) System Performance Test
• Relay Replacement (Within an Electrical Center)
• Relay Replacement (Attached to Wire Harness)
• Checking Aftermarket Accessories
• Leak Testing
• Noise Diagnosis - HVAC Module
• Noise Diagnosis - Air Conditioning (A/C) System
• Noise Diagnosis - Blower Motor
• Odor Diagnosis
• Air Delivery Description and Operation
• Air Temperature Description and Operation
• Heating Performance Diagnostic
• Instrument Panel Accessory Trim Plate Replacement (Acadia)
• Fastener Caution
• Quarter Lower Rear Trim Panel Replacement (Acadia with TB5)
• Quarter Lower Rear Trim Panel Replacement (Traverse with TB5)
• Rear Wheelhouse Panel Liner Replacement
• Lifting and Jacking the Vehicle
• Radiator Grille Replacement (Acadia)
• DTC B0158
• Air Temperature Description and Operation
• Air Delivery Description and Operation
• Sensor Resistance Table
• Actuator Recalibration

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