How to Troubleshoot the Heating and A/C Systems (Without Climate Control)

How to Troubleshoot the Heating and A/C Systems

How to Use the Self-Diagnostic Function

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

1. Turn the ignition switch to LOCK (0), and then back to ON (II).

2. Set the FAN CONTROL dial to OFF, the TEMPERATURE CONTROL dial on Max Cool, and select the VENT mode.

3. Press and hold the RECIRCULATION button, then within 10 seconds press and release the REAR WINDOW DEFOGGER/MIRROR DEFOGGER button five times. Release the RECIRCULATION button; the recirculation indicator blinks two times, then the self-diagnosis begins.

NOTE:

- The blower motor will run at various speeds when in the self-diagnostic mode.
- Once the self-diagnostic function is finished, the recirculation indicator blinks, and the number of blinks indicates the Diagnostic Trouble Code (DTC) number. If there are multiple DTCs, the indicator blinks each DTC in sequence from the lowest DTC number to the highest.
- The indicator pauses 3 seconds, then repeats the DTC blink sequence.
- If no DTCs are found, the indicator does not blink.





Example of DTC Indication Pattern (DTC 3)





Example of DTCs Indication Pattern (DTC 2 and 4)










Clear the DTCs

When the problem is repaired, DTCs will automatically clear.

Max Cool Position Function

When the mode control button is in the MAX A/C position, the HVAC control unit will automatically select the recirculation mode and turn the A/C on. If the RECIRCULATION button is pressed when in MAX A/C mode, MAX A/C turns off. If the air conditioning button is pressed when in MAX A/C mode, the A/C turns off.