Patent ID: 7464749

Claim:
An air-conditioning unit comprising: an air-conditioning case forming an air path therein; a heater for heating air passing therethrough, the heater being disposed in the air-conditioning case; a bypass path bypassing the heater; an air-mixing chamber in which cool air flowing through the bypass path and hot air passed through the heater are mixed; an air-mixing door disposed in the air-conditioning case to adjust an air-flow ratio between an air amount passing through the heater and an air amount passing through the bypass path; at least one air opening disposed in the air-conditioning case at an air downstream side of the air-mixing chamber; an auxiliary door arranged in series with the air-mixing door in the bypass path; the auxiliary door being operated between a first position and a second position, the auxiliary door in the first position closing the bypass path more than in the second position; the air-mixing door is operated between a maximum cooling position in which the air-mixing door fully opens the bypass path and fully closes the heater, and a maximum heating position in which the air-mixing door fully closes the bypass path and fully opens the heater; the auxiliary door is operated at the first position as the air-mixing door opens the bypass oath from the maximum heating position; the auxiliary door is operated at the first position when the air-mixing door is operated at the maximum heating position; the auxiliary door is operated at the second position when the air-mixing door is operated at the maximum cooling position; dimensions of the auxiliary door are smaller than dimensions of the bypass path; the auxiliary door overlaps with only a part of the bypass path; and the auxiliary door is disposed in the air-conditioning case where the air-mixing door begins to open the bypass path.