Temperature, Air Intake Control
Temperature Control

The temperature control knob regulates the temperature of the air flowing from the ventilation system. To change the cabin air temperature, turn the knob clockwise for warmer air or counterclockwise for cooler air.
Air Intake Control

Used to select the outside (fresh) air position or the recirculated air position. To change the position of the air intake control, press the control button.
Recirculated Air Position

When the recirculation position is selected, air from the passenger compartment passes through the heating system and is heated or cooled depending on the selected function.
Outside (Fresh) Air Position

If the recirculation mode is not selected or is turned off, outside air enters the vehicle and is heated or cooled depending on the selected function.
Operating the heater in recirculation mode for a long time (without air conditioning) may cause the windshield and side windows to fog up and the air inside the vehicle may become stuffy.
In addition, operating the air conditioner for a long time with the recirculation mode selected will cause the cabin air to become excessively dry.
WARNING! Limited Visibility
Continuous use of the climate control system in recirculation mode may increase humidity inside the vehicle, which may cause the windows to fog up and reduce visibility.
WARNING: Recirculated Air
Continued use of the climate control system in recirculation mode may cause drowsiness, and loss of vehicle control. Set the air intake to the outside (fresh) air position as much as possible while driving.
WARNING: Sleeping with the Air Conditioner On
Do not sleep in the vehicle with the air conditioning or heating on, as this may result in serious injury or death due to decreased oxygen levels and/or body temperature.
Test yourself
A quick Kia Rio YB quiz: every answer comes with an explanation and a link to the manual page.