A system for controlling an air heat exchanger of a vehicle includes an information collector which collects environmental information including a current speed of a vehicle, a desired air mass flow rate, and an ambient temperature. A storage stores the environmental information therein. A controller calculates a driving load and a cooling load in accordance with the environmental information and calculating a control amount of an air heat exchanger, at which a cost function that is a sum of the driving load and the cooling load is minimum.