Buick Regal: Symptoms - HVAC Systems - Automatic

NOTE: The following steps must be completed before using the symptom tables:

1. Perform the Diagnostic System Check - Vehicle before using the HVAC System Malfunction procedure in order to verify that all of the following are true:

• There are no DTCs set.
• The control modules can communicate via the serial data link.

2. Review the system operation in order to familiarize yourself with the system functions. Refer to Automatic HVAC Description and Operation.

Visual/Physical Inspection

NOTE: Shutting one or more outlets may adversely affect the Automatic HVAC system by producing erroneous duct air temperature sensor readings in the duct connecting to the closed outlet. Where possible, always operate the Automatic HVAC system with all outlets open.

• Inspect for aftermarket devices which may affect the operation of the HVAC System.
• Inspect the easily accessible or visible system components for obvious damage or conditions which may cause the symptom.
• Verify the A/C compressor turns freely and is not seized.
• Verify that the customer is using the correct key to enable personalization and is not inadvertently activating auxiliary HVAC controls.
• The A/C compressor will not operate in cold outside air temperatures.
• The following conditions may 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 HVAC System Malfunction in order to diagnose the symptom.

HVAC SYSTEM 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 Aids

Check the following mechanical fault sources:

• Air distribution box
• Air distribution hoses/air distribution ducts

Reference Information

Schematic Reference

HVAC Wiring Schematics

Connector End View Reference

Component Connector End View Index

Description and Operation

Automatic HVAC 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

NOTE: Check for bulletins before proceeding.

1. Ignition ON.

2. Verify every applicable scan tool switch parameter changes when pressing the appropriate switch on the A26 HVAC Controls.

• If any parameter does not change

Replace the A26 HVAC Controls.

• Go to next step: If all parameters change

3. Verify the blower motor operates properly with the blower motor switch in each speed position.

• If the blower motor does not operate properly in each speed position

Refer to DTC B0193.

• Go to next step: If the blower motor operates properly in each speed position

4. Verify the HVAC doors listed below move when operating the appropriate control.

• Driver Temperature
• Passenger Temperature
• Mode
• Recirculation
• If any HVAC door does not move

Refer to DTC B0223, B022A, B0233, B023A, B0408, or B0418.

• Go to next step: If all HVAC doors move

5. Install the appropriate ACR Air Conditioning Service Center, ignition ON.

6. Verify the high side pressure on the gauge is within 10% of the scan tool A/C High Side Pressure Sensor parameter.

• If the A/C High Side Pressure Sensor parameter is not within 10%

Refer to DTC P0532 or P0533.

• Go to next step: If the A/C High Side Pressure Sensor parameter is within 10%

7. Verify the A/C High Side Pressure Sensor parameter is between 269-2929 kPa (39-425 PSI).

• If the reading is not between 269-2929 kPa (39-425 PSI)

Refer to Air Conditioning (A/C) System Performance Test

• Go to next step: If the reading is between 269-2929 kPa (39-425 PSI)

8. Verify the scan tool parameters listed below are within 10% of ambient temperature.

• Lower Left Duct Air Temperature Sensor
• Upper Left Duct Air Temperature Sensor
• Lower Right Duct Air Temperature Sensor
• Upper Right Duct Air Temperature Sensor
• A/C Evaporator Temperature Sensor
• If not within 10% of ambient temperature

Refer to DTC B0173, B0178, B0509, B0514 or B3933.

• Go to next step: If within 10% of ambient temperature

9. Verify the scan tool parameters listed below are within 10% of actual conditions.

• Passenger Compartment Humidity
• Passenger Compartment Humidity Sensor Temperature
• Passenger Compartment Windshield Temperature
• If not within 10% of actual conditions

Refer to DTC B018A, B048C, B048F, or B1395.

• Go to next step: If within 10% of actual conditions

10. Engine ON, A/C system ON.

11. Verify cool air flows from the ducts with the temperature control in the coldest position.

• If the air is not cool

1. Verify the Q2 A/C Compressor Clutch is engaged.
   • If the Q2 A/C Compressor Clutch is not engaged, refer to Air Conditioning Compressor Malfunction.
   • If the Q2 A/C Compressor Clutch is engaged, refer to Air Conditioning (A/C) System Performance Test and DTC B393B.

• Go to next step: If the air is cool

12. Verify warm air flows from the ducts with the temperature control in the warmest position.

• If the air is not warm

Refer to Heating Performance Diagnostic.

• Go to next step: If the air is warm

13. Engine OFF, ignition ON.

14. Verify the scan tool Sunload parameter changes while covering the B10B Ambient Light/Sunload Sensor with a shop towel or other suitable item.

• If the Sunload parameter does not change

Refer to DTC B0163 or DTC B0183.

• Go to next step: If the Sunload parameter changes

15. Verify the actual inside air temperature, using a thermometer, is less than 3ºC (5ºF) difference from the scan tool Inside Passenger Compartment Air Temp. Sensor parameter.

• If greater than a 3ºC (5ºF) difference

  Refer to DTC B0163 or DTC B0183.

• Go to next step: If less than a 3ºC (5ºF) difference

16. Verify the G36 Auxiliary Heater Coolant Pump turns On and Off when commanded with a scan tool.

• If the G36 Auxiliary Heater Coolant Pump does not turn On and Off

  Refer to DTC B269A, B269C, or B269D.

• Go to next step: If the G36 Auxiliary Heater Coolant Pump does turn On and Off

17. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• HVAC Component Replacement Reference
• Control Module References for control module replacement, programming and setup.

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