VEHICULAR AIR-CONDITIONING APPARATUS AND AIR-CONDITIONING METHOD OF VEHICULAR AIR-CONDITIONING APPARATUS

A controller performs a prior determination by determining whether air cooling of a passenger compartment by free cooling control is possible based on a target value of a temperature in the passenger compartment that is set in advance, an outdoor air temperature, and an indoor temperature. The controller also performs a free cooling execution determination by determining whether to perform the free cooling control by comparing (i) a free cooling performance value that depends on a temperature difference between the outdoor air temperature and the indoor temperature and indicates a capacity of air cooling by the free cooling control, and (ii) an indoor heat load value that depends on a vehicle occupancy rate of passengers in the passenger compartment and indicates a difficulty of a temperature decrease in the passenger compartment.