the air input through the air paths to areas of the inside of the vehicle, and the defrost opening, the vent opening, and the floor opening are selectively open or closed by doors according to a mode, an evaporator installed at an entrance of the air paths to perform heat exchange to make the air passing through the evaporator in a low temperature state so as to cool the inside of the vehicle, a heater core installed at the rear side of the evaporator to perform heat exchange to make the air passing through the heater core in a hot temperature state so as to heat the inside of the vehicle, a first variable wall installed between the evaporator and the heater core to separate the air pathsinto upper and lower portions, or connect the separated air paths, and open or close a heated air path of the heater core, a temp door installed at the upper portion of the first variable wall between the evaporator and the heater core to adjust a degree of opening or closing of a cooled air path bypassing the heater core, and a second variable wall installed at the rear side of the heater core to separate the air passing through the heater core into upper and lower portions or connect the separated air paths, wherein the first variable wall and the temp door are independently controlled so that a path of the air passing through the evaporator can be varied.
The first variable wall comprises first and second wall