Buick Enclave: Specifications, Diagnostic Information and Procedures
SPECIFICATIONS
FASTENER TIGHTENING SPECIFICATIONS
Fastener Tightening Specifications
SENSOR RESISTANCE TABLE
Sensor Resistance Table
SCHEMATIC WIRING DIAGRAMS
HVAC SYSTEM WIRING SCHEMATICS
Power, Ground, Blower Control and Subsystem References
Fig. 1: Power, Ground, Blower Control and Subsystem References Wiring
Schematics
Actuators
Fig. 2: Actuators Wiring Schematics
Compressor Controls and Temperature Sensors
Fig. 3: Compressor Controls and Temperature Sensors Wiring Schematics
Rear HVAC
Fig. 4: Rear HVAC Wiring Schematics
DIAGNOSTIC INFORMATION AND PROCEDURES
DIAGNOSTIC CODE INDEX
DTC B0158: OUTSIDE AIR TEMPERATURE SENSOR
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category.
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
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
- The HVAC control module detects the sensor signal circuit is less than -35ºC (-39ºF).
- The HVAC control module detects the sensor signal circuit is more than 85ºC (185ºF).
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
- The DTC will become history if the HVAC control module no longer detects a failure.
- 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
- Air Delivery Description and Operation
- Air Temperature Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- 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 -35ºC (-39ºF) and 85º C (185ºF) and change with ambient air temperature changes.
Circuit/System Testing
IMPORTANT: If the ambient air temperature sensor is in temperatures below 2ºC (35ºF) the compressor clutch will be disabled until the vehicle is driven above 45 mph (72 km/h), the ignition is OFF for more than 3 hours or an instant OAT update is performed.
IMPORTANT: An instant 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 circuit and convert the A/C permission from withheld to granted.
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 -35ºC (-39ºF).
- 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 85ºC (185ºF).
- 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.
IMPORTANT: An instant OAT update must be performed to grant A/C permission after testing or replacing the ambient air temperature sensor.
Component Testing
1. Test the ambient air temperature sensor by varying the sensor temperature while monitoring the sensor resistance.
IMPORTANT: Sensor Resistance Table for this test. A thermometer can be used to test the sensor off the vehicle in warm and or cold water.
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.
- Ambient Air Temperature Sensor Replacement (Enclave, Traverse) , Ambient Air Temperature Sensor Replacement (Acadia)
- Control Module References for HVAC control module replacement, setup and programming
DTC B0228, B0413, B0433, B3779 OR B3782: RECIRCULATE POSITION FEEDBACK/TEMPERATURE CONTROL 1-3 FEEDBACK/AIR FLOW CONTROL 9-10 FEEDBACK
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC B0228 02
- Recirculate Position Feedback Circuit Short to Ground
DTC B0228 04
- Recirculate Position Feedback Circuit Open
DTC B0228 05
- Recirculate Position Feedback Circuit Short to Battery or Open
DTC B0228 08
- Recirculate Position Circuit Actuator Stalled
DTC B0228 61
- Recirculate Position Circuit Actuator Stuck
DTC B0413 02
- Temperature Control 1 Feedback Circuit Short to Ground
DTC B0413 04
- Temperature Control 1 Feedback Circuit Open
DTC B0413 05
- Temperature Control 1 Feedback Circuit Short to Battery or Open
DTC B0413 08
- Temperature Control 1 Feedback Circuit Actuator Stalled
DTC B0413 61
- Temperature Control 1 Feedback Circuit Actuator Stuck Open
DTC B0433 02
- Temperature Control 3 Feedback Circuit Short to Ground
DTC B0433 04
- Temperature Control 3 Feedback Circuit Open
DTC B0433 05
- Temperature Control 3 Feedback Circuit Short to Battery or Open
DTC B0433 08
- Temperature Control 3 Circuit Actuator Stalled
DTC B0433 61
- Temperature Control 3 Circuit Actuator Stuck
DTC B3782 02
- Air Flow Control 10 Feedback Circuit Short to Ground
DTC B3782 04
- Air Flow Control 10 Feedback Circuit Open
DTC B3782 05
- Air Flow Control 10 Feedback Circuit Short to Battery or Open
DTC B3782 08
- Air Flow Control 10 Circuit Actuator Stalled
DTC B3782 61
- Air Flow Control 10 Circuit Actuator Stuck
DTC B3779 02
- Air Flow Control 9 Feedback Circuit Short to Ground
DTC B3779 05
- Air Flow Control 9 Feedback Circuit Short to Battery or Open
DTC B3779 08
- Air Flow Control 9 Circuit Actuator Stalled
DTC B3779 61
- Air Flow Control 9 Circuit Actuator Stuck
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.
- DTC B0228 is for the recirculate actuator
- DTC B0413 is for the left air temperature actuator
- DTC B0433 is for the auxiliary air temperature actuator
- DTC B3782 is for the auxiliary mode actuator
- DTC B3779 is for the mode actuator
Conditions for Running the DTC
- The ignition is ON.
- The HVAC module is ON.
Conditions for Setting the DTC
The actual door position differs from the commanded door position by more than 4 counts or the HVAC control module detects the door position signal circuit is less than 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
- The DTC becomes history when the HVAC control module no longer detects the condition that set the DTC.
- The history DTC will clear after 100 fault-free ignition cycles.
Reference Information
Schematic Reference
HVAC Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
Description and Operation
- Air Delivery Description and Operation
- Air Temperature Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
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 reading should be between 3 and 253 counts.
Circuit/System Testing
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 less than 3 counts.
- If greater 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 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. Ignition OFF, 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 OFF, 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.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Temperature Valve Actuator Replacement - Right Side
- Temperature Valve Actuator Replacement - Left Side
- Mode Valve Actuator Replacement
- Air Inlet Valve Actuator Replacement
- Auxiliary Temperature Valve Actuator Replacement
- Auxiliary Mode Valve Actuator Replacement
- Control Module References for HVAC control module and HVAC Auxiliary control module or rear seat audio (RSA) replacement, setup and programming.
DTC B1023: INTEGRAL SWITCH PERFORMANCE
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC B1023 05
- Integral Switch Performance Short to Ground
DTC B1023 06
- Integral Switch Performance Short to Battery or Open
DTC B1023 61
- Integral Switch Performance Signal Invalid
Circuit/System Description
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.
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 or shorted 5 volt reference circuit.
Conditions for Clearing the DTC
- A current DTC clears when the malfunction is no longer present.
- A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
Reference Information
Schematic Reference
HVAC Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
Description and Operation
- Air Temperature Description and Operation
- Air Delivery Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
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.
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
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC B3933 02
- Evaporator Air Temperature Sensor Short to Ground
DTC B3933 05
- Evaporator Air Temperature Sensor Short to Battery or Open
Diagnostic Fault Information
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
- The DTC will become history if the HVAC control module no longer detects a failure.
- 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
- Air Temperature Description and Operation
- Air Delivery Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
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.
- 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.
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.
- If not within the specified range, replace the sensor.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Evaporator Air Temperature Sensor Replacement
- Control Module References for HVAC control module replacement, setup and programming
DTC P0532 OR P0533: AIR CONDITIONING A/C REFRIGERANT PRESSURE SENSOR
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC P0532
- Air Conditioning A/C Refrigerant Pressure Sensor Circuit Low Voltage
DTC P0533
- Air Conditioning A/C Refrigerant Pressure Sensor Circuit High Voltage
Diagnostic Fault Information
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
- The ECM detects that the A/C pressure is less than 1 psi (0.01 volt) sets DTC P0532.
- The ECM detects that the A/C pressure is greater than 425 psi (4.90 volts) sets DTC P0533.
Action Taken When the DTC Sets
- The ECM will not illuminate the malfunction indicator lamp (MIL).
- The ECM stores the failure records.
- The A/C compressor clutch is disabled.
Conditions for Clearing the DTC
- The DTC will become history if the ECM no longer detects a failure.
- 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.
Reference Information
Schematic Reference
HVAC Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
Description and Operation
- Air Temperature Description and Operation
- Air Delivery Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
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.
- 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.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement
- Control Module References for the ECM replacement, setup and programming
DTC P0645, P0646 OR P0647: AIR CONDITIONING (A/C) COMPRESSOR CLUTCH RELAY
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P0645
- Air Conditioning (A/C) Compressor Clutch Relay Control Circuit
DTC P0646
- Air Conditioning (A/C) Compressor Clutch Relay Control Circuit Low Voltage
DTC P0647
- Air Conditioning (A/C) Compressor Clutch Relay Control Circuit High Voltage
Diagnostic Fault Information
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
- The ignition voltage is between 11-18 volts.
- The engine speed is greater than 600 RPM.
- An A/C request is made.
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:
- Battery voltage is between 9-18 volts.
- Engine coolant temperature (ECT) is less than 123ºC (253ºF).
- Engine speed is greater than 600 RPM.
- Engine speed is less than 4, 760 RPM.
- A/C high side pressure is between 269-2929 kPa (39-425 psi)-Refer to Air Conditioning (A/C) System Performance Test.
- Throttle position is less than 100%.
- Evaporator temperature is greater than 0ºC (32ºF).
- ECM does not detect excessive torque load.
- ECM does not detect insufficient idle quality.
- The ambient temperature is above 1ºC (34ºF).
Reference Information
Schematic Reference
HVAC Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
Description and Operation
- Air Delivery Description and Operation
- Air Temperature Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
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
- Ignition OFF.
- 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
- Ignition OFF.
- 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,
- Disconnect the harness connector at the Q2 A/C compressor clutch.
- 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
- Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
- 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
- Ignition OFF.
- 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
- Ignition OFF, disconnect the harness connector at the K20 engine control module,
- 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
- Ignition OFF.
- 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
- Ignition OFF, disconnect the harness connector at the Q2 A/C compressor clutch.
- 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:
- 30 and 86
- 30 and 87
- 30 and 85
- 85 and 87
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.
- Air Conditioning Compressor Replacement
- Relay Replacement (Within an Electrical Center) , Relay Replacement (Attached to Wire Harness)
- Air Conditioning Clutch Assembly Replacement
- Control Module References for HVAC control module and ECM replacement, setup and programming
SYMPTOMS - HVAC SYSTEMS - MANUAL
IMPORTANT: Review the system operation in order to familiarize yourself with the system functions. Refer to the following procedures:
- Air Delivery Description and Operation
- Air Temperature Description and Operation
Visual/Physical Inspection
- Inspect for aftermarket devices which could affect the operation of the HVAC System. Refer to Checking Aftermarket Accessories.
- Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
- Verify the A/C compressor clutch turns freely and is not seized.
- The A/C compressor will not operate in cold outside air temperatures. Refer to Air Temperature Description and Operation.
- 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
- 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:
- Blower Motor Malfunction
- Air Conditioning Compressor Malfunction
- Air Temperature Malfunction
- Auxiliary Blower Motor Malfunction
- Air Recirculation Malfunction
- Noise Diagnosis - Air Conditioning (A/C) System
- Noise Diagnosis - Blower Motor
- Odor Diagnosis
AIR CONDITIONING COMPRESSOR MALFUNCTION
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Circuit/System Description
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.
Diagnostic Aids
The following conditions must be met in order for the ECM to turn on the compressor clutch:
- Battery voltage is between 9-18 volts.
- Engine coolant temperature (ECT) is less than 123ºC (253ºF).
- Engine speed is less than 4760 RPM.
- Engine speed is more than 600 RPM.
- A/C high side pressure is between 2929-269 kPa (425-39 psi).
- Throttle position is less than 100 percent.
- Evaporator temperature is greater than 0ºC (32ºF)
- ECM does not detect excessive torque load
- ECM does not detect insufficient idle quality.
Reference Information
Schematic Reference
HVAC Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
Scan Tool Reference
Control Module References for Scan Tool Information
Circuit/System Testing
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.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Air Conditioning Clutch Assembly Replacement
- Air Conditioning Compressor Replacement
- Control Module References for HVAC control module and ECM replacement, setup and programming
BLOWER MOTOR MALFUNCTION
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
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.
Reference Information
Schematic Reference
HVAC Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
Description and Operation
- Air Delivery Description and Operation
- Air Temperature Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
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.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Blower Motor Replacement
- Control Module References for blower motor control module and HVAC control module setup, replacement and programming
AUXILIARY BLOWER MOTOR MALFUNCTION
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
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% to 90% duty cycle (PWM), 90% is high speed fan.
Reference Information
Schematic Reference
HVAC Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
Description and Operation
- Air Delivery Description and Operation
- Air Temperature Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
1. Ignition OFF and all vehicle systems OFF, disconnect the X2 harness connector at the K8A Blower Motor Control Module - Auxiliary. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal 5 and ground.
If 10 ohms or greater
- 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
3. Ignition ON.
4. Verify a test lamp illuminates between the B+ circuit terminal 6 and ground.
If the test lamp does not illuminate and the circuit fuse is good
- Ignition OFF, remove the test lamp.
- 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
- Ignition OFF, remove the test lamp.
- Test for infinite resistance between the B+ circuit terminal 6 and
ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- If infinite resistance
- Disconnect the X1 harness connector at the K8A Blower Motor Control Module - Auxiliary and disconnect the harness connector at the M8B Blower Motor - Auxiliary.
- Test for infinite resistance between the M8B Blower Motor - Auxiliary B+
terminal A and ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- If infinite resistance, test or replace the M8B Blower Motor - Auxiliary.
If the test lamp illuminates
5. Ignition OFF, remove the test lamp and disconnect the X4 harness connector at the K33 HVAC Control Module, ignition ON.
6. Test for less than 1 V between the K8A Blower Motor Control Module - Auxiliary control circuit terminal 3 and ground.
If 1 V or greater
Repair the short to voltage on the circuit.
If less than 1 V
7. Ignition OFF.
8. 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
9. 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
10. Connect the harness connectors at the K8A Blower Motor Control Module - Auxiliary and the K33 HVAC Control Module and disconnect the harness connector at the M8B Blower Motor - Auxiliary, ignition ON and blower ON.
11. Verify a test lamp illuminates between the B+ circuit terminal B and ground.
If the test lamp does not illuminate
- Ignition OFF, disconnect the X2 harness connector at the K8A Blower Motor Control Module - Auxiliary.
- 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 replace the K8A Blower Motor Control Module - Auxiliary.
If the test lamp illuminates
12. Connect a test lamp between the control circuit terminal B and the B+ circuit terminal A.
13. Verify the test lamp becomes progressively brighter as the blower speed is increased and progressively dimmer as the blower speed is decreased.
If the test lamp does not illuminate
- Ignition OFF, disconnect the X1 harness connector at the K8A Blower Motor Control Module - Auxiliary, ignition ON.
- Test for less than 1 V between the M8B Blower Motor - Auxiliary control
circuit terminal B and
ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V
- 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 K8A Blower Motor Control Module - Auxiliary.
- Verify the symptom or DTC was corrected.
- If the symptom or DTC was not corrected, replace the K33 HVAC Control Module.
- If the symptom or DTC was corrected
- All OK.
If the test lamp illuminates, but does not change in brightness
- Ignition OFF, disconnect the X1 harness connector at the K8A Blower Motor Control Module - Auxiliary.
- 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 K8A Blower Motor Control Module - Auxiliary.
If the test lamp changes in brightness as the blower speed is changed
14. Test or replace the M8B Blower Motor - Auxiliary.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Auxiliary Blower Motor Replacement
- Control Module References for HVAC control module replacement, setup and programming
AIR TEMPERATURE MALFUNCTION
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
Air Temperature Sensors
The air temperature sensors are a 2-wire negative temperature co-efficient thermistor. The vehicle uses the following air temperature sensors:
- Ambient Air Temperature Sensor
- 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 +101ºC (-40 to +215ºF). 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.
Diagnostic Aids
Reference Information
Schematic Reference
HVAC Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
Description and Operation
- Air Delivery Description and Operation
- Air Temperature Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
Scan Tool Reference
Control Module References for Scan Tool Information
Circuit/System Verification
1. Measure actual outside air temperature
