a cooling heat exchanger configured to exchange heat between air to be blown into an interior of the vehicle and a refrigerant of a refrigerant cycle, and to cool the air;

a temperature detector configured to detect a cooling temperature of the air cooled by the cooling heat exchanger;

a compressor that is driven by an engine of the vehicle and is configured to compress and discharge the refrigerant of the refrigerant cycle;

a target temperature setting unit configured to set a target cooling temperature of the air cooled by the cooling heat exchanger;

a compressor control unit configured to control an operation of the compressor based on the cooling temperature and the target cooling temperature; and

a traveling state determination unit configured to determine a traveling state of the vehicle, wherein

the target temperature setting unit is configured to set a first target temperature as the target cooling temperature when the traveling state determination unit determines that the vehicle is in a traveling condition in which a vehicle traveling speed exceeds 0 and a deceleration traveling is not performed, and to set a second target temperature higher than the first target temperature as the target cooling temperature when the traveling state determination unit determines that the vehicle starts decelerating, and

the compressor control unit is configured to cause the compressor to stop operating when the traveling state determination unit determines that the vehicle starts decelerating, and to cause the compressor to start operating based on the cooling temperature and the second target temperature as the target cooling temperature when the cooling temperature detected by the temperature detection unit is equal to or higher than the second target temperature in the deceleration traveling.