Try the following.

HOW TO RETRIEVE A DTC

The heater control panel has a self-diagnosis function.

Running the Self-diagnosis Function

1. Turn the ignition switch ON (II).

2. Turn the fan switch OFF, and the recirculation control switch to Recirculate (recirculation indicator comes on).

3. Press and hold the recirculation control switch to Fresh (recirculation indicator goes off). Continue to hold the switch until the recirculation indicator comes on for 2 seconds, then it will blink the Diagnostic Trouble Code (DTC) to indicate a
faulty component.

Resetting the Self-diagnosis Function

Turn the ignition switch OFF to cancel the self-diagnosis function. After completing repair work, run the self-diagnosis function again to make sure that there are no other malfunctions.

# 2 is not written very clearly. #3- where does the DTC code blink? This troubleshooting guide is not written clearly at all.

What is it you don't understand so I can help?