Conditions for Incipient Windshield Fogging and Anti-Fog Strategy for Automatic Climate Control

This paper describes a strategy, suitable for use in a climate control ATC (Automatic Temperature Controller) for predicting the onset or existence of fog (or misting) conditions and automatically taking action to avoid or reduce such conditions. Two variables currently measured by the ATC, cabin air temperature and ambient (outside) temperature are combined with cabin air relative humidity information provided by an additional sensor to allow the calculation of a degree of likelihood of windshield/window fogging. As fogging conditions are approached, a staged alteration of climate control strategy can relieve or even avoid altogether windshield fogging.