A vehicle cooling/heating system includes a coolant line in which coolant is circulated between a heat source component of a vehicle that provides waste heat and a chiller and a refrigerant line in which refrigerant is circulated through a compressor, a condenser, an expansion valve, and an evaporator. The refrigerant line performs indoor cooling through the evaporator. A controller controls the coolant line such that, during a drying mode in which it is necessary to dry the evaporator, the coolant in the coolant line is circulated or not circulated through the heat source component and the chiller, and such that the refrigerant in the refrigerant line flows, in order, through the compressor, the evaporator, and the chiller.