HVAC System Malfunction

HVAC System Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions 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 Schematics HVAC - Manual

Connector End View Reference

Component Connector End Views Sunshade - Left

Description and Operation

Manual HVAC Description and Operation HVAC - Manual

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Special Tools

J43600 - ACR Air Conditioning Service Center

Circuit/System Verification

Note: Check for bulletins before proceeding.

1. Ignition ON.

2. Verify the scan tool Blower Motor Switch parameter changes when rotating the blower switch through each speed position.

• If the parameter does not change for each speed position
Replace the A26 HVAC Controls.

• If the parameter changes for each speed position

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

• If the blower motor does not operate in each speed position
Refer to DTC B0193 HVAC - Manual

• If the blower motor operates properly in each speed position

4. Verify the scan tool parameters listed below change when pressing the appropriate switch.

* Left Temperature Knob Position

* Air Recirculation Mode Switch

* Bi-Level Switch

• If any parameter does not change
Replace the A26 HVAC Controls

• If all parameters change

5. Verify the HVAC doors listed below move when pressing the appropriate switch.

* Temperature

* Bi-Level mode

* Recirculation

• If any HVAC door does not move
Refer to DTC B0223, B0233, B023A, or B0408 HVAC - Manual

• If all HVAC doors move

6. Install the J43600 - Air Conditioning Service Center.

7. Verify the high side pressure reading on the Air Conditioning Service Center is within 10% of the scan tool A/C High Side Pressure Sensor parameter.

• If the reading is not within 10%
Refer to DTC P0532 or P0533 HVAC - Manual

• If the reading is within 10%

8. 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 Air Conditioning (A/C) System Performance Test.

• If the reading is between 269-2929 kPa (39-425 PSI)

9. Engine ON, A/C system ON.

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

• If the air is not cool

1. Observe the Q2 A/C Compressor Clutch.

2. Verify the Q2 A/C Compressor Clutch is engaged.

• If the Q2 A/C Compressor Clutch is not engaged
Refer to DTC P0645, P0646, or P0647 HVAC - Manual.

• If the Q2 A/C Compressor Clutch is engaged
Refer to Air Conditioning (A/C) System Performance Test Air Conditioning (A/C) System Performance Test and DTC B393B HVAC - Manual.

• If the air is cool

11. 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 Heating Performance Diagnostic.

• If the air is warm

12. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

* HVAC Component Replacement Reference HVAC Component Replacement Reference

* Control Module References Control Module References for HVAC control module replacement, programming, and setup.