Vehicle air conditioner having refrigerant cycle with heating function

In a vehicle air conditioner, a refrigerant cycle system is constructed to switch a cooling refrigerant cycle (C) where an interior heat exchanger (18) is used as an evaporator, and a hot gas heater cycle (H) where the interior heat exchanger is used as a radiator. Further, it is determined whether the interior heat exchanger has a quantity of retained water in a heating mode due to the hot gas heater cycle. When it is determined that the quantity of retained water is in the interior heat exchanger in the heating mode, operation of a compressor (10) of the refrigerant cycle system is intermittently controlled so that temperature of air blown from the interior heat exchanger becomes lower than temperature of a vehicle windshield.