The vehicle's front and rear seats have adjustable head restraints. The head restraints provide comfort for passengers, but more importantly they are designed to help protect passengers from whiplash and other neck and spinal injuries during an accident, especially in a rear impact collision.
WARNING
To reduce the risk of serious injury or death in an accident, take the following precautions when adjusting your head restraints:

NOTICE
To prevent damage, NEVER hit or pull on the head restraints.
Armrest
Front seat head restraintsHyundai Elantra AD (2016-2020) Service Manual: Heater Core Repair procedures
Replacement
1.
Disconnect the negative (-) battery terminal.
2.
Remove the heater and blower assembly.
(Refer to Heater - "Heater Unit")
3.
Remove the heater core cover (A) after loosening the mounting screws.
4.
Pull out the heater core (A) from the heater unit.
5.
To intall, ...
Hyundai Elantra AD (2016-2020) Service Manual: Seat Heater Switch Repair procedures
Removal
[Front Seat]
1.
Disconnect the negative (-) battery terminal.
2.
Remove the floor console assembly.
(Refer to Body - "Floor Console Assembly")
[Rear Seat]
1.
Disconnect the negative (-) battery terminal.
2.
Remove the rear door window switch.
(Refer to Power Windows - "Po ...