defogging

This is because most defogging is achieved within that timeframe, after which the vehicle's heater has usually brought the interior of the vehicle to a warm enough temperature that the fog does not recur.

For primary defogging, heat is generally provided by the vehicle's engine coolant via the heater core; fresh air is blown through the heater core and then ducted to and distributed over the interior surface of the windshield by a blower.