HVAC System - Manual Buick Enclave I

Fastener Tightening Specifications

Fastener Tightening Specifications

Sensor Resistance Table

Sensor Resistance Table

Scheme 1

Scheme 2

Scheme 3

Scheme 4

Diagnostic Code Index

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

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 compressor clutch operation.

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

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

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

Circuit/System Verification

Ignition ON, observe the ambient air temperature sensor. The reading should be between -35°C (-39°F) and 85°C (185°F) and change with ambient air temperature changes.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the ambient air temp sensor.
2. Ignition OFF, test for less than 10 ohms of resistance 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 Ambient 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 3 A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Ambient 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 Temperature VS 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.

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 B0433 is for the auxiliary air temperature actuator
4. DTC B3782 is for the auxiliary mode actuator
5. 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

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

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 appropriate actuator in both directions with a scan tool. The reading should be between 3 and 253 counts.

1. Ignition OFF, disconnect the harness connector at the appropriate actuator.
2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal 8 and ground. It may take up to 5 minutes for all vehicle systems to power down. 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 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.
4. 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.
5. 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.
6. 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.
7. 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.
8. Connect a test lamp between control circuit terminal 5 and control circuit terminal 6.
9. 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.
10. If both circuits test normal, test or replace the actuator.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Temperature Valve Actuator Replacement - Right Side»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
2. «Temperature Valve Actuator Replacement - Left Side»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic)
3. «Mode Valve Actuator Replacement»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual)
4. «Air Inlet Valve Actuator Replacement»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual)
5. «Auxiliary Temperature Valve Actuator Replacement»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual)
6. «Auxiliary Mode Valve Actuator Replacement»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual)
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 may be set by an open or shorted 5 volt reference circuit to the auxiliary HVAC control module or an 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 or shorted 5 volt reference circuit.

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

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

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

1. Ignition ON, disconnect the harness connector at the auxiliary HVAC control module, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 3 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.
2. Reprogram the HVAC control module that set DTC B1023. The module should successfully reprogram. If the module will not reprogram, replace the HVAC control module that set the DTC.
3. With a scan tool, clear the DTC.
4. Ignition OFF.
5. 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.

Circuit Description

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

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

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.

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.

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

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

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.

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

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

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 - Manual

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/manual-hvac-system/#hvac-system-manual__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/manual-hvac-system/#hvac-system-manual)
2. «Air Conditioning Compressor Malfunction»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual)
3. «Air Temperature Malfunction»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual)
4. «Auxiliary Blower Motor Malfunction»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual)
5. «Air Recirculation Malfunction»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual)
6. «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)
7. «Noise Diagnosis - Blower Motor»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__noise-diagnosis-blower-motor)
8. «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.

When the A/C switch is pressed, the HVAC control module grounds the A/C request signal circuit. This input will request the ECM to ground the A/C compressor clutch relay control circuit, which will switch the A/C CMPRSR CLUTCH relay. 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 less than 4760 RPM.
4. Engine speed is more than 600 RPM.
5. A/C high side pressure is between 2929-269 kPa (425-39 psi).
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.

Schematic Reference

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

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 connector X2, terminal 8 ground circuit terminal at the HVAC control module.
2. Test for less than 1.0 ohm of resistance between the ground circuit terminal 2 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Remove the A/C compressor clutch relay.
4. Verify that a test lamp illuminates between the relay coil B+ circuit terminal 85 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
5. Verify that a test lamp illuminates between the relay switch B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the relay switch B+ circuit for an open/high resistance. If the A/C clutch fuse is open, test the relay switch control circuit for a short to ground. If all circuits test normal, test or replace the A/C compressor clutch.
6. Disconnect the harness connector at the A/C compressor clutch terminal 1.
7. Ignition OFF test for less than 1.0 ohm of resistance between the A/C compressor ground circuit terminal 2 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
8. Connect the harness connector at the A/C compressor clutch.
9. Connect a 10-amp fused jumper wire between the relay switch B+ circuit terminal 30 and the relay switch control circuit terminal 87. Verify the A/C compressor clutch engages. If the A/C compressor clutch does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the A/C compressor.
10. Connect a test lamp between the relay control circuit terminal 86 and the relay coil B+ circuit terminal 85.
11. Using a scan tool, command the A/C relay output ON and OFF. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp remains ON all the time, test for a short to ground on the control circuit connector X1 terminal 53. If the circuit tests normal, replace the ECM. If the test lamp remains OFF all the time, test for a short to voltage or an open/high resistance on the control circuit. If the circuit tests normal, replace the ECM.
12. If all circuits test normal, test or replace the A/C compressor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Air Conditioning Clutch Assembly Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
2. «Air Conditioning Compressor Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
3. «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.

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

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

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.

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

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

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.

Air Temperature Sensors

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. A/C Evaporator 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 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 temperature sensor will 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 corrected.

Schematic Reference

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

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. 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 / Inside Air Temperature Sensor Circuit Malfunction.
2. Measure actual inside air temperature using a thermometer. Compare this value to the scan tool Inside Air Temp. parameter. The measured temperature should be within 5 degrees of parameter. If not within the specified range, refer to Ambient Temperature Sensor Circuit Malfunction.
3. Measure actual temperature using a thermometer at the A/C evap. temperature sensor. Compare this value to the scan tool A/C Evap. Temperature Sensor parameter. The measured temperature should be within 5 degrees of the parameter. If not within the specified range, refer to Evaporator Temperature Sensor Circuit Malfunction.

Ambient Temperature Sensor Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate temp sensor.
2. Test for less than 1 ohm of resistance between the low reference circuit terminal B and ground. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.
3. Ignition ON, verify the appropriate scan tool Temp Sensor Voltage parameter is greater than 4.9 volts or 250 counts. If less than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the HVAC control module.
4. Install a 3-amp fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Temp Sensor Voltage parameter is less than 0.1 volt or 5 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.
5. If all circuits test normal, test or replace the appropriate temp sensor.

Evaporator Temperature Sensor Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate temp sensor.
2. Test for less than 1.0 ohm of resistance 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, verify the appropriate temp sensor parameter is greater than 4.9 volts or 250 counts. If less than the specified range, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the HVAC control module.
4. Install a 3-amp fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the scan tool temp sensor parameter is less than 0.1 volt or 5 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.
5. If all circuits test normal, test or replace the appropriate temp sensor.

1. Ignition OFF, disconnect the harness connector at the appropriate temp 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 diagnostic procedure.

1. «Evaporator Air Temperature Sensor Replacement»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
2. «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)

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 auxiliary HVAC control assembly is an input to the primary HVAC control module. The primary HVAC control module uses a low reference circuit and a 5-volt reference circuit to determine the position of the auxiliary HVAC control switches. The auxiliary HVAC assembly has 3 signal circuits to relay the desired mode, temperature and blower motor speeds to the primary HVAC control module. The primary HVAC control module uses this input to adjust the desired positions of the mode, temperature and blower motor.

Schematic Reference

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

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 ON, verify DTC B0433 or B3782 is not set. If either of the DTCs are set, refer to «DTC B0228, B0413, B0423, B0433, B3779, or B3782»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic) , (RPO CJ2) or «DTC B0228, B0413, B0433, B3779, or B3782»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual) (RPO C67 or CJ3).
2. Individually adjust each of the controls on the auxiliary HVAC control assembly. Verify that the auxiliary blower motor, temperature actuator and Mode actuator move properly to the selected positions or desired speeds.

1. Ignition OFF, disconnect the harness connector at the auxiliary HVAC control assembly.
2. Ignition OFF, test for less than 1 ohm between the low reference circuit terminal 4 and ground. If greater than the specified range , test the low reference circuit for an open/high resistance.
3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 3 and ground. If greater than the specified range, test the 5-volt reference circuit for an short to voltage. If less than the specified range, test the 5-volt reference circuit for an short to ground or an open/high resistance.
4. Ignition OFF, connect the harness connector at the auxiliary HVAC control assembly. Disconnect the X1 harness connector at the HVAC control module.
5. Ignition ON, verify voltage at the signal circuit terminal 19 varies between 0.5-4.5 volts while varying the auxiliary blower speed from low to high. If not within the specified range, test the signal circuit for a short to voltage, a short to ground, or an open/high resistance. If the circuit tests normal, test or replace the auxiliary HVAC control assembly.
6. Verify voltage at the signal circuit terminal 8 varies between 0.5-4.5 volts while varying the auxiliary temperature setting from warm to cool. If not within the specified range, test the signal circuit for a short to voltage, a short to ground, or an open/high resistance. If the circuit tests normal, test or replace the auxiliary HVAC control assembly.
7. Verify voltage at the signal circuit terminal 9 varies between 0.5-4.5 volts while selecting the three mode positions. If not within the specified range, test the signal circuit for a short to voltage, a short to ground, or an open/high resistance. If the circuit tests normal, test or replace the auxiliary HVAC control assembly.
8. Ignition OFF, connect the X1 harness connector at the HVAC control module.
9. Ignition ON, verify the auxiliary blower motor speed changes while varying the blower speed setting on the auxiliary HVAC control assembly. If the blower speed does not vary, refer to «Auxiliary Blower Motor Malfunction»(/buick/enclave/i-2007-2013/remont/automatic-hvac-system/#hvac-system-automatic) , (RPO CJ2) or «Auxiliary Blower Motor Malfunction»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual) (RPO C67 or CJ3).
10. If all circuits test normal, replace the HVAC control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Auxiliary Heater and Air Conditioning Control Module Replacement»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual)
2. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) 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 recirculation actuator is a 5-wire bi-directional electric motor that incorporate a feedback potentiometer. Low reference, 5-volt reference, position signal, and 2 control circuits enable the actuators 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. This gives the actuator the power to adjust the air source being used from fresh air to recirculation (cabin air). When the actuator shaft rotates, the potentiometer's adjustable contact changes the door position signal between 0-5 volts.

Schematic Reference

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

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. Turn ON the ignition, with the engine OFF.
2. Place the blower motor switch at the maximum speed position.
3. Place the mode switch in the vent or panel position.
4. Place the recirculation switch in the recirc position.
5. Place the recirculation switch in the fresh air position.
6. Observe the air inlet door commanded parameter in the scan tool.

The scan tool air in let commanded counts parameter should change.

1. Ignition OFF, disconnect the recirc actuator harness connector at the recirculation actuator.
2. Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit terminal 1 and ground. If greater than 1.0 ohm, 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 to 5.2 volts between the 5-volt reference circuit terminal 3 and ground. If less than 4.8 volts, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC control module. If greater than 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the HVAC control module.
4. Verify the appropriate scan tool parameter is less than 3 counts. If greater than the specified range, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the HVAC control module.
5. Install a 3 A fused jumper wire between the signal circuit terminal 2 and the low reference circuit terminal 1. Verify the appropriate scan tool actuator parameter is greater than 250 counts. 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.
6. Connect a test lamp between control circuit A terminal 5 and control circuit B terminal 6.
7. Command the actuator in both directions with a scan tool (air inlet door command). The test lamp should turn ON and OFF with each command. If the test lamp remains always ON or always OFF during either commands, test for an open, short to ground, or short to voltage on either control circuit. If the circuit tests normal, replace the HVAC control module.
8. If all circuits test normal, replace the recirculation actuator.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Control Module References»(/buick/enclave/i-2007-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC replacement, setup, and programming.
2. «Air Inlet Valve Actuator Replacement»(/buick/enclave/i-2007-2013/remont/manual-hvac-system/#hvac-system-manual)

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

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

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.

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 5

HVAC Control Module Replacement

Scheme 6

Temperature Valve Actuator Replacement - Right Side

Scheme 7

Mode Valve Actuator Replacement

Scheme 8

Air Inlet Valve Actuator Replacement

Scheme 9

Auxiliary Heater and Air Conditioning Control Module Replacement

Scheme 10

Auxiliary Temperature Valve Actuator Replacement

Scheme 11

Auxiliary Mode Valve Actuator Replacement

Air Delivery Description and Operation

The air delivery description and operation is divided into 4 areas

1. HVAC Control Components
2. Air Speed
3. Air Delivery
4. Recirculation 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 desired 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 HVAC control module provides blower, air delivery mode, air temperature settings and input signals to auxiliary HVAC control module. The HVAC system assembly receives power from battery input with ignition 3 voltage circuit as a backup.

The HVAC control module supports the following features

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.

Front 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.

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.

Air Speed

Front Blower Motor Control Processor

The front blower motor control processor is an interface between front HVAC control module and front blower motor. The front blower control processor regulates supply voltage and ground circuits to front blower motor. The front HVAC control module provides a blower speed signal to the control processor in order to command the desired blower motor speed. The control processor uses the blower motor ground as a low side control to adjust the blower motor speed.

The blower motor forces air to circulate within the vehicle's interior. The vehicle operator determines the blower motors speed by placing the blower motor switch in a desired speed position or by selecting automatic operation. In manual operation, once a blower speed is selected, the blower speed remains constant, until a new speed is selected. In automatic operation, the HVAC control module will determine what blower speed is necessary in order to achieve or maintain a desired temperature.

As the requested blower speed increases, the following conditions occur

1. The HVAC control module increases the amount of time that the blower motor speed control circuit is modulated to ground.
2. The voltage and duty cycle, measured between the blower motor speed control circuit and ground, decrease.

As the requested blower speed decreases, the following conditions occur

1. The HVAC control module decreases the amount of time that the blower motor speed control circuit is modulated to ground.
2. The voltage and duty cycle, measured between the blower motor speed control circuit and ground, increase.

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.

Auxiliary Blower Motor Control Processor

The auxiliary blower motor control processor is an interface between the auxiliary HVAC control module and the rear blower motor. The auxiliary blower motor control processor monitors supply voltage and ground circuits to the rear blower motor. The auxiliary HVAC control module provides a pulse width modulation (PWM) signal to the control processor in order to command the blower motor speed. The auxiliary blower motor control processor uses the blower motor ground as a low side control to adjust the blower motor speed.

The blower motor forces air to circulate within the vehicles interior. The vehicle operator determines the blower motors speed by placing the blower motor switch in a desired speed position or by selecting automatic operation. In manual operation, once a blower speed is selected, the blower speed remains constant, until a new speed is selected. In automatic operation, the HVAC control module will determine what blower speed is necessary in order to achieve or maintain a desired temperature.

As the requested blower speed increases, the following conditions occur

1. The HVAC control module increases the amount of time that the blower motor speed control circuit is modulated to ground.
2. The voltage and duty cycle, measured between the blower motor speed control circuit and ground, decrease.

As the requested blower speed decreases, the following conditions occur

1. The HVAC control module decreases the amount of time that the blower motor speed control circuit is modulated to ground.
2. The voltage and duty cycle, measured between the blower motor speed control circuit and ground, increase.

Air Delivery

Front Control

The HVAC control module controls the distribution of air by the use of recirculation and mode actuators. 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 a fault is detected within the mode door travel, the HVAC control module will drive the actuator to defrost, which is a default position for the mode door actuator. Turning the mode door position to either defrost or defog positions, the HVAC control module will move the recirculation actuator to outside air reducing window fogging. When defrost/defog is selected, the A/C compressor is activated. The A/C compressor clutch will engage when ambient temperatures are above 3°C (38°F). A/C is available in all modes. Recirculation is only available in Panel and Bi-Level modes. The rear window defogger does not affect the HVAC system.

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 the air temperature setting. The HVAC control module will have the ability to override the auxiliary HVAC control module by placing it in any position other than auxiliary.

The auxiliary mode switch in the HVAC control module allows the driver to direct the air flow in the rear of the vehicle between the floor, headliner, or a blend between the 2 options. Power is provided to both front and auxiliary HVAC control modules from I/P fuse block on the ignition 3 voltage circuit.

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. 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. When Defrost or Defog positions are selected outside air is circulated to the windshield to reduce fogging. 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.

Dual Zone Operation

The HVAC control module uses dual temperature button switches. The dual zone controls allows for maximum temperature offset between and comfort between the driver and passenger. It is possible to select maximum airflow over the evaporator core with one dual zone switch along with maximum airflow over the heater core with the other dual zone switch. Each air temperature actuator is independent from the other and the passenger side is not limited in it's range of temperature offset.

Remote Start

Remote Start Activation

The following describes the HVAC control head functionality upon receiving the remote start active serial data message and a power mode status is set to off/awake. During remote start on the manual HVAC system the blower motor, mode doors, temperature doors, recirc door and A/C request will be set to the current setting on the control panel when the vehicle was last turned off. The rear defrost will be activated and the heated seats will be disabled.

Remote Start De-activation

When the remote start is exited, GMLAN power mode equals run mode or remote start engine. In the case of manual settings, the displays will revert to the actual state of operation of the features, on the basis of their normal control algorithms.

Air Temperature Description and Operation

The air temperature controls are divided into 5 areas

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

HVAC Control Module

The HVAC control module is a GMLAN device that interfaces between the operator and the HVAC system to maintain desired 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 HVAC control module provides blower, air delivery mode, air temperature settings and input signals to auxiliary HVAC control module. The HVAC system assembly receives power from battery input with ignition 3 Voltage circuit as a backup.

The HVAC control module supports the following features

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.

Front 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 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.

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

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 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 3234 kPa. The clutch will be enabled after the pressure decreases to less than 1931 kPa.

The HVAC control module uses dual temperature button switches. The dual zone controls allows for maximum temperature offset between and comfort between the driver and passenger. It is possible to select maximum airflow over the evaporator core with one dual zone switch along with maximum airflow over the heater core with the other dual zone switch. Each air temperature actuator is independent from the other and the passenger side is not limited in it's range of temperature offset.

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. Regardless of the temperature setting, the following can affect 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 manual HVAC system is a dual temperature zone system. There are 2 separate air temperature levers. Moving the air temperature levers to the upward position diverts most of the airflow through the heater core, which increases the outlet air temperature. Moving the air temperature levers to the most downward position diverts most of the airflow around the heater core, which decreases the outlet air temperature. The right air temperature actuator controls the duct air temperature flowing through the center console to the second row seating passengers. The air temperature offset can be as much as 16.7°C (30°F).

Pressing the A/C button enables the HVAC control module to request A/C compressor engagement and turn ON the A/C button LED. The HVAC control module sends a GMLAN message to the Powertrain Control Module (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. Defrost and Defog mode selections will request A/C operation but not turn ON the A/C LED.

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 3234 kPa.
4. A/C compressor temperature switch contacts are closed.
5. PCM receives an A/C request from the HVAC control module.
6. Engine coolant temperature (ECT) is less than 124°C.
7. The engine RPM is less than 5,800 RPM.

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
5. Outside air temperature

The A/C compressor has an A/C compressor temperature switch. This switch protects the compressor from over heating. The switch interrupts power to the compressor clutch coil. When the compressor core temperature rises above 124°C (255°F) the switch opens, disabling the compressor clutch coil. When the temperature lowers to 120°C (248°F) the switch closes, enabling the compressor clutch coil. This switch is not a serviceable part, it is integral to the A/C compressor.

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

1. Ambient air temperature is less than 4°C (39°F).
2. A/C compressor temperature switch contacts are open.
3. Throttle position is 100 percent.
4. The A/C low pressure switch is open.
5. A/C high side pressure is more than 1931 kPa.
6. A/C low side pressure is less than 151 kPa (22 psi).
7. Engine coolant temperature (ECT) is more than 124°C.
8. Engine speed is more than 5,800 RPM.
9. Transmission shift
10. PCM detects excessive torque load.
11. PCM detects insufficient idle quality.
12. PCM detects a hard launch condition.

Auxiliary Heating and A/C Operation

The auxiliary air temperature switch is a rotary knob switch. Turning the air temperature switch to the warmest position diverts most of the airflow through the heater core, which increases the outlet air temperature. Turning the air temperature switch to the coolest position diverts most of the airflow around the heater core, which decreases the outlet air temperature.

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.

A/C Cycle

Refrigerant is the key element in an air conditioning system. R-134a is presently the only EPA approved refrigerant for automotive use. R-134a is an very low temperature gas that can transfer the undesirable heat and moisture from the passenger compartment to the outside air.

The A/C compressor is belt driven and operates when the magnetic clutch is engaged. The compressor builds pressure on the vapor refrigerant. Compressing the refrigerant also adds heat to the refrigerant. The refrigerant is discharged from the compressor, through the discharge hose, and forced to flow to the condenser and then through the balance of the A/C system. The A/C system is mechanically protected with the use of a high pressure relief valve. If the A/C refrigerant pressure sensor were to fail or if the refrigerant system becomes restricted and refrigerant pressure continued to rise, the high pressure relief will pop open and release refrigerant from the system.

Compressed refrigerant enters the condenser in a high temperature, high pressure vapor state. As the refrigerant flows through the condenser, the heat of the refrigerant is transferred to the ambient air passing through the condenser. Cooling the refrigerant causes the refrigerant to condense and change from a vapor to a liquid state.

The condenser is located in front of the radiator for maximum heat transfer. The condenser is made of aluminum tubing and aluminum cooling fins, which allows rapid heat transfer for the refrigerant. The semi-cooled liquid refrigerant exits the condenser and flows through the liquid line, to the orifice tube.

The orifice tube is located in the liquid line between the condenser and the evaporator. The orifice tube is the dividing point for the high and the low pressure sides of the A/C system. As the refrigerant passes through the orifice tube, the pressure on the refrigerant is lowered. Due to the pressure differential on the liquid refrigerant, the refrigerant will begin to vaporize at the orifice tube. The orifice tube also meters the amount of liquid refrigerant that can flow into the evaporator.

Refrigerant exiting the orifice tube flows into the evaporator core in a low pressure, liquid state. Ambient air is drawn through the HVAC module and passes through the evaporator core. Warm and moist air will cause the liquid refrigerant boil inside of the evaporator core. The boiling refrigerant absorbs heat from the ambient air and draws moisture onto the evaporator. The refrigerant exits the evaporator through the suction line and back to the compressor, in a vapor state, and completing the A/C cycle of heat removal. At the compressor, the refrigerant is compressed again and the cycle of heat removal is repeated.

The conditioned air is distributed through the HVAC module for passenger comfort. The heat and moisture removed from the passenger compartment will also change form, or condense, and is discharged from the HVAC module as water.

A/C Cycle with Auxiliary

The auxiliary A/C system operates from the vehicles primary A/C system. The front or primary A/C system must be ON to allow the rear A/C system to function.

Refrigerant is the key element in an air conditioning system. R-134a is presently the only EPA approved refrigerant for automotive use. R-134a is an very low temperature gas that can transfer the undesirable heat and moisture from the passenger compartment to the outside air.

The A/C system used on this vehicle is a non cycling system. Non cycling A/C systems use a high pressure switch to protect the A/C system from excessive pressure. The high pressure switch will OPEN the electrical signal, to the compressor clutch, in the event that the refrigerant pressure becomes excessive. After the high and low side of the A/C system pressure equalize, the high pressure switch will CLOSE. Closing the high pressure switch will complete the electrical circuit to the compressor clutch. The A/C system is also mechanically protected with the use of a high pressure relief valve. If the high pressure switch were to fail or if the refrigerant system becomes restricted and refrigerant pressure continued to rise, the high pressure relief will pop open and release refrigerant from the system.

The A/C compressor is belt driven and operates when the magnetic clutch is engaged. The compressor builds pressure on the vapor refrigerant. Compressing the refrigerant also adds heat to the refrigerant. The refrigerant is discharged from the compressor, through the discharge hose, and forced to flow to the condenser and then through the balance of the A/C system.

Compressed refrigerant enters the condenser in a high temperature, high pressure vapor state. As the refrigerant flows through the condenser, the heat of the refrigerant is transferred to the ambient air passing through the condenser. Cooling the refrigerant causes the refrigerant to condense and change from a vapor to a liquid state.

The condenser is located in front of the radiator for maximum heat transfer. The condenser is made of aluminum tubing and aluminum cooling fins, which allows rapid heat transfer for the refrigerant. The semi-cooled liquid refrigerant exits the condenser and flows through the liquid line. The liquid line flow is split and the liquid refrigerant flows to both the front or primary A/C system, and to the liquid line for the rear A/C system.

The liquid refrigerant, flowing to the rear A/C system, flows into the rear thermal expansion value (TXV). The rear TXV is located at the rear evaporator inlet. The TXV is the dividing point for the high and the low pressure sides of the rear A/C system. As the refrigerant passes through the TXV, the pressure on the refrigerant is lowered. Due to the pressure differential on the liquid refrigerant, the refrigerant will begin to boil at the expansion device. The TXV also meters the amount of liquid refrigerant that can flow into the evaporator.

Refrigerant exiting the TXV flows into the evaporator core in a low pressure, liquid state. Ambient air is drawn through the rear A/C module and passes through the evaporator core. Warm and moist air will cause the liquid refrigerant boil inside of the evaporator core. The boiling refrigerant absorbs heat from the ambient air and draws moisture onto the evaporator. The refrigerant exits the evaporator through the suction line and back to the primary A/C systems suction line. Refrigerant in the primary A/C system suction line flows back to the compressor, in a vapor state, and completes the A/C cycle of heat removal. At the compressor, the refrigerant is compressed again and the cycle of heat removal is repeated.

The conditioned air is distributed through the rear A/C module for passenger comfort. The heat and moisture removed from the rear passenger compartment will also change form, or condense, and is discharged from the rear A/C module as water.

Special Tools

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

Scheme 12

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
• Ambient Air Temperature Sensor Replacement (Enclave,Traverse)
• Air Temperature Description and Operation
• Air Delivery Description and Operation
• Sensor Resistance Table
• 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
• Noise Diagnosis - Air Conditioning (A/C) System
• Noise Diagnosis - Blower Motor
• Odor Diagnosis
• Instrument Panel Accessory Trim Plate Replacement (Acadia)
• Fastener Caution
• Actuator Recalibration
• Quarter Lower Rear Trim Panel Replacement (Acadia with TB5)
• Quarter Lower Rear Trim Panel Replacement (Traverse with TB5)
• Rear Wheelhouse Panel Liner Replacement
• DTC B0158
• Air Delivery Description and Operation
• Air Temperature Description and Operation
• Sensor Resistance Table