Vehicle air conditioner

A vehicle air conditioner comprising:

• a heat pump device including a compressor which compresses a refrigerant, an interior heat exchanger provided inside a vehicle cabin, an exterior heat exchanger provided outside the vehicle cabin, an expansion valve, and an exterior blower which blows air toward the exterior heat exchanger, the heat pump device being formed by connecting together the compressor, the interior heat exchanger, the expansion valve, and the exterior heat exchanger via refrigerant piping;
• an air-conditioning controller configured to control the heat pump device;
• and
• a frosting state detecting means for detecting a frosting state of the exterior heat exchanger,
• the heat pump device being configured to be switched by the air-conditioning controller between multiple operation modes including a heating operation mode and a defrosting operation mode, wherein
• the exterior heat exchanger includes a plurality of heat-transfer pipes which run vertically and are arranged side-by-side horizontally when installed and the vehicle is on level ground and a header tank which is connected to an end of the heat-transfer pipes and which extends horizontally,
• the header tank has a refrigerant inlet portion and a refrigerant outlet portion which are provided along the length of the header tank so as to be spaced apart from each other, and a partition which partitions the heat-transfer pipes into a plurality of paths such that a refrigerant flow that goes from the refrigerant inlet portion toward the refrigerant outlet portion is formed,
• the exterior blower includes a first fan and a second fan which are arranged horizontally along an air passage plane of the exterior heat exchanger so as to be located closer to the refrigerant inlet and the refrigerant outlet, respectively,
• the airflow rate of the second fan is set to be higher than the airflow rate of the first fan such that the flow rate of the air being blown by the second fan to pass through one of the paths closer to a refrigerant outlet of the exterior heat exchanger is higher than the flow rate of the air being blown by the first fan to pass through another one of the paths closer to a refrigerant inlet of the exterior heat exchanger than the one of the paths, and
• the air-conditioning controller is configured to switch, if the frosting state detecting means senses, during the heating mode of operation, that the exterior heat exchanger is frosted, the operation modes of the heat pump device into a defrosting operation mode in which the air-conditioning controller initially stops the first and second fans and then activates the first and second fans independently of each other according to the degree of defrosting of the exterior heat exchanger during the defrosting mode of operation.