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 - Automatic
Connector End View Reference

Component Connector End Views Hybrid/EV Battery Pack X1 A4
Description and Operation

Automatic HVAC Description and Operation HVAC - Automatic
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

Circuit/System Verification

Note: Check for bulletins before proceeding.

1. Ignition ON, place the blower motor switch in each speed position. Verify that the blower motor operates properly in each position.

• If the blower motor does not operate properly in all speeds, refer to DTC B0193 B0193.

2. Using the scan tool observe the mode, temperature, air inlet and recirculation door positions. Verify the actual and commanded door positions are within 4 counts of each other.

• If not within the specified range, refer to Circuit/System Testing DTC B0223, B0233, B023A, or B0408 B0223

3. Engine ON, A/C ON, place the temperature control in the coldest position. Verify that cool air flows from the ducts in the vehicle.

• If the air is not cool, refer Air Conditioning (A/C) System Performance Test. Air Conditioning (A/C) System Performance Test
4. Turn the A/C OFF and place the temperature control in the warmest position.

• If the air is insufficiently heated refer to Heating Performance Diagnostic Heating Performance Diagnostic.

5. Engine OFF, ignition ON, cover the sunload sensor assembly with a shop towel or other suitable item. Verify the scan tool Sunload Sensor parameter changes.

• If it does not change, refer to Circuit/System Testing DTC B0163, B0183, or B1405 B0163.

6. Measure actual inside air temperature using a thermometer. Compare this value to the scan tool Inside Passenger Compartment Air Temp. Sensor parameter. The measured temperature should be within 5 degrees of parameter.

• If not within the specified range, refer to Circuit/System Testing DTC B0163, B0183, or B1405 B0163.

7. Ignition ON, observe the scan tool A/C Evaporator Temperature Sensor parameter. The reading should be between -39°F (-35°C) and 185°F (85°C) and change with evaporator air temperature changes.

• If not within the specified range, refer to Circuit/System Testing DTC B3933 B3933 or DTC P0536-P0538 or P15B3 P0536.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

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