
The mode selection button controls the direction of the air flow through the ventilation system.
The air flow outlet direction is cycled as follows:

Face-Level (B, D)

Air flow is directed toward the upper body and face. Additionally, each outlet can be controlled to direct the air discharged from the outlet.
Bi-Level (B, C, D, E)

Air flow is directed towards the face and the floor.
Floor-Level (A, C, D, E)

Most of the air flow is directed to the floor, with a small amount of the air being directed to the windshield and side window defrosters.
Floor & Defrost (A, C, D, E)

Most of the air flow is directed to the floor and the windshield with a small amount directed to the side window defrosters.

Defrost-Level (A, D)
Most of the air flow is directed to the windshield with a small amount of air directed to the side window defrosters.
Manual Heating and Air Conditioning
Instrument panel ventsHyundai Elantra AD (2016-2020) Owners Manual: Vehicle Load Limit
Two labels on your driver's door sill show how much weight your vehicle was designed
to carry: the Tire and Loading Information Label and the Certification Label.
Before loading your vehicle, familiarize yourself with the following terms for
determining your vehicle’s weight ratings, from ...
Hyundai Elantra AD (2016-2020) Service Manual: Blower Resistor (Manual) Repair procedures
Inspection
1.
Measure the resistance between the terminals.
2.
The measured resistance is not within specification, the blower resistor must be replaced. (After removing the resistor)
Replacement
1.
Disconnect the negative (-) battery terminal.
2.
Remove the crash pad center panel.
...