Hyundai Elantra N Owner's Manual page 217

Convenience Features
Information
Operating the system primarily in Fresh
mode is recommended. Use Recirculation
mode temporarily only when needed.
Prolonged operation of the heater in
Recirculation mode and without the A/C
ON can cause fogging of the windshield.
In addition, prolonged use of the A/C
ON in Recirculation mode may result in
excessively dry, dehumidified air in the
cabin and may promote formation of
musty vent odor due to stagnant air.
WARNING
Continued use of the climate control
system operation in Recirculation
mode for a prolonged period of
time may cause drowsiness to the
occupants in the cabin. This may lead
to loss of vehicle control which may
lead to an accident.
Continued use of the climate control
system operation in Recirculation
mode with the A/C OFF may allow
humidity to increase inside the cabin.
This may cause condensation to
accumulate on the windshield and
obscure visibility.
Do not sleep in your vehicle or
remain parked in your vehicle with
the windows up and either the
heater or the air conditioning ON for
prolonged periods of time. Doing so
may increase the levels of carbon
dioxide in the cabin which may lead
to serious injury or death.
5-96
Fan speed control
The fan speed can be set to the desired
speed by using the fan speed control
toggle switch.
More air is delivered with higher fan
speeds.
Pressing the OFF button turns off the fan.
NOTICE
Operating the fan speed when the
Engine Start/Stop button is in the ON
position could cause the battery to
discharge. Operate the fan speed when
the engine is running.
OCN7050118