For normal operation of the heater, set the air intake mode selection switch to the outdoor air intake mode, and the ventilation mode selection knob to the position (to the leg area) .
For faster heating, set the air intake mode selection switch to air recirculation mode.
If the windows fog up, set the ventilation mode selection knob to the position (to the windshield and side window heating vents) , and the air intake mode selection switch to air recirculation mode.
For maximum heating, set the air temperature control knob to the position "Warm" (Hot air).