The A/C MAX mode is used to cool the inside of the vehicle more quickly. Air flow is directed toward the upper body and face.
In this mode, the air conditioning and the recirculated air position will be selected automatically.
After the vehicle interior has cooled down initially, resume using normal A/C mode. Continuous use of A/C MAX mode is not recommended.
Hyundai Sonata LF 2014-2019 Service Manual: AVN Remote Controller Schematic Diagrams
Circuit Diagram
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Hyundai Sonata LF 2014-2019 Owners Manual: Child Restraint System (CRS)
Children Always in the Rear
WARNING
Always properly restrain children in the rear seats of the vehicle.
Children of all ages are safer when restrained in the rear seat. A child riding
in the front passenger seat can be forcefully struck by an inflating air bag resulting
in SERIOUS INJURY or DEATH. ...