New power plant like clean diesel engine, hybrid, and supercharged petrol engine requires additional heat exchangers in front end of the vehicles. By this, power of cooling system is increased, and improvement of fuel consumption by new power sources is reduced. In new technology “SLIM”, operation of one heat exchanger is changeable by various driving conditions. Heat load of a condenser of AC system and that of an additional heat exchanger like CAC or sub-radiator for diesel engine or hybrid vehicles are changeable by vehicle speed or engine load. Using this conception, heat exchangers of front end of a vehicle is made compact by 30% and more.