1. A method for controlling a vehicle cooling system that includes an engine, an exhaust gas recirculation (EGR) cooler, an oil cooler, a heater, a radiator, and a controller, wherein the engine, the EGR cooler, the oil cooler, the heater, and the radiator are respectively connected through a coolant line and coolant circulates through the engine, the EGR cooler, the oil cooler, the heater, and the radiator by operation of a water pump, and the controller for controlling a control valve that receives the coolant from the engine and is connected to the oil cooler, the heater, and the radiator, respectively, the method comprising:sensing, by the controller, a plurality of driving conditions; and
operating, by the controller, the control valve when a warm mode is required to increase a temperature within the vehicle based on the sensed driving conditions,
wherein the control valve is operated based on a first mode, a second mode, and a third mode based on a coolant temperature, and
wherein, in the operation of the control valve, the first mode, the second mode, and the third mode are executed sequentially.