How to Troubleshoot the Heating/Air Conditioning

How to Use the Self-diagnostic Function


The HVAC control unit has a self-diagnostic function for heating, ventilation, and air conditioning system. To run the self-diagnostic function, do the following:

1.Turn the ignittion switch OFF.

2.Press and hold the recirculation control and rear window defogger buttons, and turn the ignition switch ON (II).

3.Recirculation indicator turns on for 2 seconds, then self-diagnostic function begins.

NOTE:
  • The blower motor will run at any speed regardless of the dial positioning.
  • In the case of multiple problems, the recirculation indicator will blink the lowest number DTC only.
  • If no DTCs are found, the indicator will not blink.

 

Example of DTC indication Pattern (DTC 3). 

DTC (Recirculation Indicator Blinks) Detection Item 
An open in the air mix control motor circuit 
A short in the air mix control motor circuit 
A problem in the air mix control linkage, door, or motor 
An open or short in the mode control motor circuit 
A problem in the mode control linkage, doors, or motor 
A problem in the blower motor circuit 
HVAC control unit internal error 
An open in the evaporator temperature sensor circuit 
A short in the evaporator temperature sensor circuit 

Clear the DTCs


1.Turn the ignition switch OFF.

2.Set fan control dial OFF, temperature control dial on MAX COOL.

3.Press and hold the ventilation and recirculation control buttons, turn the ignition switch ON (II).

4.Ventilation indicator turns on for 2 seconds, then DTC clear.

NOTE: After completing repair work, run the self-diagnostic function again to make sure that there are no other malfunctions.