Patent 7779900 was granted and assigned to Denso on August, 2010 by the United States Patent and Trademark Office.
Both an air mixing door (9) for the cold air for adjusting a passage area of the cold air passage (6); and an air mixing door (10) for the hot air for adjusting a passage area of the hot air passage (7) are composed of a sliding door for adjusting the passage area when the air mixing door (9) for the cold air and the air mixing door (10) for the hot air are slid in a direction perpendicular to the flow of air in both the passages (6, 7), and while one of the air mixing door (9) for the cold air and the air mixing door (10) for the hot air is maintaining one of the passages (6, 7) in a fully opened state, an operating position of the other door is adjusted so that a passage area of the other passage is adjusted and a temperature of the air blowing out into a vehicle compartment is adjusted.