The instrument panel vent air flow can be directed up/down or left/right using the vent adjustment lever.
The air flow can also be closed using the vent adjustment lever. To close the instrument panel vents, slide the vent adjustment lever to the LEFT until it clicks.
Hyundai Elantra AD (2016-2020) Service Manual: Canister Close Valve (CCV) Specifications
Specification
ItemSpecificationCoil Resistance (?)19.5 ~ 22.5 [20°C(68°F)]
...
Hyundai Elantra AD (2016-2020) Owners Manual: Child-Protector Rear Door locks
The child safety lock is provided to help prevent children seated in the rear
from accidentally opening the rear doors. The rear door safety locks should be used
whenever children are in the vehicle.
The child safety lock is located on the edge of each rear door. When the child
safety lock ...