Mode Selection

The mode selection button controls the direction of airflow through the ventilation system.
The air outlet direction changes as follows:

Face Level (B, D)

Airflow is directed to the upper body and face. In addition, each vent can be adjusted to direct the air flowing out of the outlet.
Bi-Level (B, C, D, E)

Airflow is directed to the face and floor.
Floor Level (A, C, D, E)

Most of the airflow is directed to the floor, with a small amount directed to the windshield and side window defroster vents.
Floor and Defrost (A, C, D, E)

Most of the airflow is directed to the floor and windshield, with a small amount directed to the side window defroster vents.

Defrost Level (A, D)
Most of the airflow is directed to the windshield, with a small amount directed to the side window defroster vents.
Test yourself
A quick Hyundai Elantra AD quiz: every answer comes with an explanation and a link to the manual page.