Patent ID: 7788935

Claim:
A control method of an automatic defogging system of a vehicle when a window relative humidity in a passenger room increases and decreases, comprising: sensing a window relative humidity value through a defogging sensor installed on an inner surface of a window; comparing the sensed window relative humidity value to a preset reference value; removing humidity by selectively operating a selection mode of an air conditioning system based on the comparison of the sensed window relative humidity to the preset reference value; and controlling a temperature setting in the vehicle; wherein when the window relative humidity in the vehicle increases, removing said humidity comprises: opening an intake door and a defrost door, if the sensed value is greater than or equal to a value c and less than a value d; fully opening the defrost door, operating an air conditioner, and increasing an amount of air of a blower, if the sensed value is greater than or equal to the value d and less than a value g; converting a defrost mode and further increasing an amount of air of the blower, if the sensed value is greater than or equal to the value g and less than a value h; increasing maximally an amount of air of the blower, if the sensed value is greater than or equal to the value h; and returning to a room temperature control mode, if the sensed value is less than or equal to a value a, wherein the value a is 55 to 65%, the value c is 65 to 75%, the value d is 70 to 80%, the value g is 85 to 95%, and the value h is 90 to 100%.