Buick Enclave manuals

Buick Enclave: Specifications, Diagnostic Information and Procedures

Buick Enclave 2008-2017 Service Manual / HVAC / HVAC - Automatic / Specifications, Diagnostic Information and Procedures

SPECIFICATIONS

FASTENER TIGHTENING SPECIFICATIONS

Fastener Tightening Specifications

Buick Enclave. HVAC - Automatic

SENSOR RESISTANCE TABLE

Sensor Resistance Table

Buick Enclave. HVAC - Automatic

Buick Enclave. HVAC - Automatic

SCHEMATIC WIRING DIAGRAMS

HVAC SYSTEM SCHEMATICS

Power, Ground, Blower Control, Serial Data and Sunload Sensor

Buick Enclave. HVAC - Automatic
Fig. 1: Power, Ground, Blower Control, Serial Data And Sunload Sensor Wiring Schematic

Actuators

Buick Enclave. HVAC - Automatic
Fig. 2: Actuators Wiring Schematic

Temperature Sensors

Buick Enclave. HVAC - Automatic
Fig. 3: Temperature Sensors Wiring Schematic

Compressor Controls

Buick Enclave. HVAC - Automatic
Fig. 4: Compressor Controls Wiring Schematic

Rear HVAC

Buick Enclave. HVAC - Automatic
Fig. 5: Rear HVAC Wiring Schematic

DIAGNOSTIC INFORMATION AND PROCEDURES

DIAGNOSTIC CODE INDEX

Buick Enclave. HVAC - Automatic

Buick Enclave. HVAC - Automatic

Buick Enclave. HVAC - Automatic

DTC B0158: OUTSIDE AIR TEMPERATURE SENSOR

Diagnostic Instructions

DTC Descriptors

DTC B0158 02

Outside Air Temperature Sensor Circuit Short to Ground

DTC B0158 05

Outside Air Temperature Sensor Circuit Short to Battery or Open

Diagnostic Fault Information

Buick Enclave. HVAC - Automatic

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

Action Taken When the DTC Sets

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

Conditions for Clearing the DTC

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

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

Circuit/System Testing

IMPORTANT: An instant Outside Air Temperature (OAT) update must be performed by pressing the A/C and Recirc buttons at the same time before and after the system has been serviced to update the filtered ambient air temperature sensor.

1. Ignition OFF, disconnect the harness connector at the ambient air temp sensor.

2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal B and ground.

3. Ignition ON, verify the scan tool Outside Air Temp. Sensor Raw parameter is less than -35ºC (-39ºF).

4. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Outside Air Temp. Sensor Raw parameter is greater than 85ºC (185ºF).

5. If all circuits test normal, test or replace the ambient air temp sensor.

Component Testing

1. Test the ambient air temperature sensor by varying the sensor temperature while monitoring the sensor resistance.

2. Compare the readings with the Sensor Resistance Table and verify that the resistance is within 5% of the specification.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

DTC B0163: PASSENGER COMPARTMENT TEMPERATURE SENSOR

Diagnostic Instructions

DTC Descriptors

DTC B0163 02

DTC B0163 05

Diagnostic Fault Information

Buick Enclave. HVAC - Automatic

Circuit/System Description

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

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

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

The system operates using a default value.

Conditions for Clearing the DTC

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

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

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the inside air temp sensor.

2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal B and ground.

3. Ignition ON, verify the scan tool inside Air Temp. Sensor parameter is less than -35ºC (-39ºF).

4. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Inside Air Temp. Sensor parameter is greater than 85ºC (185ºF).

5. If all circuits test normal, test or replace the inside air temp sensor.

Component Testing

1. Test the inside air temperature sensor by varying the sensor temperature while monitoring the sensor resistance.

2. Compare the readings with the Sensor Resistance Table and verify that the resistance is within 5 percent of the specification.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

DTC B0173, B0178, B0509 OR B0514: OUTPUT AIR TEMPERATURE SENSOR 1-4

Diagnostic Instructions

DTC Descriptors

DTC B0173 02

DTC B0173 05

DTC B0178 02

DTC B0178 05

DTC B0509 02

DTC B0509 05

DTC B0514 02

DTC B0514 05

Diagnostic Fault Information

Buick Enclave. HVAC - Automatic

Buick Enclave. HVAC - Automatic

Circuit/System Description

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

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

The system operates using a default value.

Conditions for Clearing the DTC

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

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

Circuit/System Testing

IMPORTANT: If an air duct temperature sensor has an out of range condition caused by a short to voltage, short to ground or an open/high resistance, the scan tool will display the same value: 39ºF (4ºC).

1. Ignition OFF, disconnect the harness connector at the appropriate air duct temperature sensor.

2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal 2 and ground.

3. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal 1 and the low reference circuit terminal 2.

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

Component Testing

1. Test the air duct temperature sensor by varying the sensor temperature while monitoring the sensor resistance.

2. Compare the readings with the Sensor Resistance Table and verify that the resistance is within 5 percent of the specification.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

DTC B0183 OR B0188: SOLAR LOAD SENSOR 1-2

Diagnostic Instructions

DTC Descriptors

DTC B0183 02

DTC B0183 05

DTC B0188 02

DTC B0188 05

Diagnostic Fault Information

Buick Enclave. HVAC - Automatic

Circuit Description

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

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

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

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

Circuit/System Testing

IMPORTANT: If a solar load sensor has an out of range condition caused by a short to voltage, short to ground or an open/high resistance, the scan tool will display the same value: 225 counts.

1. Ignition OFF, disconnect the harness connector at the sunload sensor.

2. Test for less than 10 ohms between the ground circuit terminal C and ground.

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

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

DTC B0228, B0413, B0423, B0433, B3779 OR B3782: RECIRCULATE POSITION FEEDBACK/TEMPERATURE CONTROL 1-3 FEEDBACK

Diagnostic Instructions

DTC Descriptors

DTC B0228 02

DTC B0228 04

DTC B0228 05

DTC B0228 08

DTC B0228 61

DTC B0413 02

DTC B0413 04

DTC B0413 05

DTC B0413 08

DTC B0413 61

DTC B0423 02

DTC B0423 04

DTC B0423 05

DTC B0423 08

DTC B0423 61

DTC B0433 02

DTC B0433 04

DTC B0433 05

DTC B0433 08

DTC B0433 61

DTC B3779 02

DTC B3779 04

DTC B3779 05

DTC B3779 08

DTC B3779 61

DTC B3782 02

DTC B3782 04

DTC B3782 05

DTC B3782 08

DTC B3782 61

Circuit/System Description

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.

Conditions for Running the DTC

Conditions for Setting the DTC

The actual door position differs from the commanded door position by more than 4 counts or the HVAC control module detects the door position signal circuit is less than 3 counts or greater than 253 counts.

Action Taken When the DTC Sets

The control circuit is deactivated for the appropriate actuator.

Conditions for Clearing the DTC

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, command the appropriate actuator in both directions with a scan tool. The scan tool door position parameter reading should be between 3 and 253 counts.

Circuit/System Testing

1. Ignition OFF, disconnect all external devices to include the scan tool and battery charger. It will take more than 10 minutes for all vehicle systems to power down.

2. Disconnect the harness connector at the appropriate actuator.

3. Test for less than 10 ohms between the low reference circuit terminal 8 and ground.

NOTE: Ground measurements will be abnormally high if taken before all vehicle systems have powered down.

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

5. Verify the scan tool Door Position parameter is greater than 250 counts.

6. 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.

7. Ignition ON, test for less than 10 ohms between the control circuit terminal 5 and ground.

8. Ignition ON, test for less than 10 ohms between the control circuit terminal 6 and ground.

9. Connect a test lamp between control circuit terminal 5 and control circuit terminal 6.

10. 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.

11. If both circuits test normal, test or replace the actuator.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

DTC B1023: INTEGRAL SWITCH PERFORMANCE

Diagnostic Instructions

DTC Descriptors

DTC B1023 05

DTC B1023 06

DTC B1023 61

Circuit/System Description

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

Conditions for Running the DTC

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

Conditions for Setting the DTC

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

Conditions for Clearing the DTC

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Reprogram the HVAC control module. The module should successfully reprogram.

2. With a scan tool, clear the DTC.

3. Ignition OFF.

4. Wait 60 seconds, then recheck for DTCs. DTC B1023 should not set.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for control module replacement, setup and programming

DTC B3933: EVAPORATOR AIR TEMPERATURE SENSOR

Diagnostic Instructions

DTC Descriptors

DTC B3933 02

DTC B3933 05

Diagnostic Fault Information

Buick Enclave. HVAC - Automatic

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.

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

The A/C compressor will be disabled.

Conditions for Clearing the DTC

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

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

Circuit/System Testing

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

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.

3. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal 1 and low reference circuit terminal 2.

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

Component Testing

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 and verify that the resistance is within 5 percent of the specification.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

DTC P0532 OR P0533: AIR CONDITIONING A/C REFRIGERANT PRESSURE SENSOR

Diagnostic Instructions

DTC Descriptors

DTC P0532

DTC P0533

Diagnostic Fault Information

Buick Enclave. HVAC - Automatic

Circuit/System Description

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.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Diagnostic Aids

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

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

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.

Circuit/System Testing

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.

3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 2 and ground.

4. Verify the scan tool A/C High Side Pressure Sensor parameter is less than 0.1 volts (1 psi).

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).

6. If all circuits test normal, test or replace the A/C refrigerant pressure sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

DTC P0645, P0646 OR P0647: AIR CONDITIONING (A/C) COMPRESSOR CLUTCH RELAY

Diagnostic Instructions

DTC Descriptor

DTC P0645

DTC P0646

DTC P0647

Diagnostic Fault Information

Buick Enclave. HVAC - Automatic

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.

Conditions for Running the DTC

Conditions for Setting the DTC

P0645 or P0646

The ECM detects a short to ground or an open at the A/C compressor clutch relay control circuit.

P0647

The ECM detects a short to voltage at the A/C compressor clutch relay control circuit.

Action Taken When the DTC Sets

P0645 or P0646

The A/C compressor is inoperative or always active. The A/C compressor solenoid is commanded to 0% displacement. This causes warm air from the ducts, even with unwanted clutch engagement.

P0647

The A/C compressor is inoperative.

Conditions for Clearing the DTC

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

Diagnostic Aids

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

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the KR29 A/C compressor clutch relay, ignition ON.

2. Verify a test lamp illuminates between the B+ circuit terminal 30 and ground.

If the test lamp does not illuminate and the circuit fuse is good

  1. Ignition OFF.
  2. Test for less than 2 ohms in the B+ circuit end to end.
    • If 2 ohms or greater, repair the open/high resistance in the circuit.
    • If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.

If the test lamp does not illuminate and the circuit fuse is open

  1. Ignition OFF.
  2. Test for infinite resistance between the B+ circuit and ground.
    • If less than infinite resistance, repair the short to ground on the circuit.
    • If infinite resistance,
  3. Disconnect the harness connector at the Q2 A/C compressor clutch.
  4. Test for infinite resistance between the control circuit terminal 87 and ground.
    • If less than infinite resistance, repair the short to ground on the circuit.
    • If infinite resistance, test or replace the Q2 A/C compressor clutch.

If the test lamp illuminates

3. Ignition ON.

4. Verify a test lamp illuminates between the ignition circuit terminal 85 and ground.

If the test lamp does not illuminate

Replace the X50A underhood fuse block.

If the test lamp illuminates

5. Connect a test lamp between the ignition circuit terminal 85 and the control circuit terminal 86.

6. Verify the test lamp turns ON and OFF when commanding the Engine Control Module A/C Compressor Clutch Relay ON and OFF with a scan tool.

If the test lamp is always OFF

  1. Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
  2. Test for less than 1 V between the control circuit and ground.
    • If 1 V or greater, repair the short to voltage on the circuit.
    • If less than 1 V
  3. Ignition OFF.
  4. Test for less than 2 ohms in the control circuit end to end.
    • If 2 ohms or greater, repair the open/high resistance in the circuit.
    • If less than 2 ohms, replace the K20 engine control module.

If the test lamp is always ON

  1. Ignition OFF, disconnect the harness connector at the K20 engine control module,
  2. Test for infinite resistance between the control circuit and ground.
    • If less than infinite resistance, repair the short to ground on the circuit.
    • If infinite resistance, replace the K20 engine control module.

If the test lamp turns ON and OFF

7. Verify a test lamp does not illuminate between the control circuit terminal 87 and ground.

If the test lamp illuminates

Repair the short to voltage on the circuit.

If the test lamp does not illuminate

8. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the Q2 A/C compressor clutch. It may take up to 2 minutes for all vehicle systems to power down.

9. Test for less than 10 ohms between the ground circuit terminal 1 and ground.

If 10 ohms or greater

  1. Ignition OFF.
  2. Test for less than 2 ohms in the ground circuit end to end.
    • If 2 ohms or greater, repair the open/high resistance in the circuit.
    • If less than 2 ohms, repair the open/high resistance in the ground connection.

If less than 10 ohms

10. Connect the harness connector at the Q2 A/C compressor clutch.

11. Ignition ON, connect a 10 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87.

12. Verify the Q2 A/C compressor clutch is activated.

If the Q2 A/C compressor clutch does not activate

  1. Ignition OFF, disconnect the harness connector at the Q2 A/C compressor clutch.
  2. Test for less than 2 ohms in the control circuit end to end.
    • If 2 ohms or greater, repair the open/high resistance in the circuit.
    • If less than 2 ohms, test or replace the Q2 A/C compressor clutch.

If the Q2 A/C compressor clutch activates

13. Test or replace the KR29 A/C compressor clutch relay.

Component Testing

1. Ignition OFF, disconnect the KR29 A/C compressor clutch relay.

2. Test for 60-180 ohms between terminals 85 and 86.

If not between 60-180 ohms

Replace the KR29 A/C compressor clutch relay.

If between 60-180 ohms

3. Test for infinite resistance between the terminals listed below:

If less than infinite resistance

Replace the KR29 A/C compressor clutch relay.

If infinite resistance

4. Install a 15 A fused jumper wire between terminal 85 and 12 V. Install a jumper wire between terminal 86 and ground.

5. Test for less than 2 ohms between terminals 30 and 87.

If 2 ohms or greater

Replace the KR29 A/C compressor clutch relay.

If less than 2 ohms

6. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

SYMPTOMS - HVAC SYSTEMS - AUTOMATIC

IMPORTANT: Review the system operation in order to familiarize yourself with the system functions. Refer to the following procedures:

Visual/Physical Inspection

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:

AIR CONDITIONING COMPRESSOR MALFUNCTION

Diagnostic Instructions

Diagnostic Fault Information

Buick Enclave. HVAC - Automatic

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.

Diagnostic Aids

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

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

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

Circuit/System Testing

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.

3. Verify that a test lamp illuminates between the ignition circuit terminal 85 and ground.

4. Verify that a test lamp illuminates between the relay B+ circuit terminal 30 and ground.

READ NEXT:

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