To defog the windows as quickly as possible, start the engine, turn the fan speed control to four for maximum air flow.
Adjust the recirculate knob to draw air from the outside.
Turn the vent knob to the windshield icon.
Turn on the air conditioning system if possible to help pull moisture out of the air.
Turn to the end of the red zone for maximum heat.
If not already on, press the button in the center to turn on the rear defogger.