Hyundai Elantra MD/UD: Manual climate control system
1. Turn the ignition switch to the ON position.
2. Press the defrost button ().
3. Push the air intake control button at least 5 times.
The indicator light in the air intake control button will blink 3 times with 0.5 second of interval. It indicates that the defogging logic is canceled or returned to the programmed status.
If the battery has been discharged or disconnected, the system resets to the programmed defogging logic.