COOLING SYSTEM AND COOLING METHOD

A cooling system is provided to cool an engine of a vehicle, which includes a cooling water passage through which cooling water is supplied to a water jacket formed in the engine, and having an undercover cooling water passage provided in an undercover, a radiator provided in the cooling water passage and configured to cool the cooling water by exchanging heat with air flowing into an engine bay from a grille, a flow rate adjuster configured to adjust a cooling water flow rate supplied to the undercover cooling water passage, and a controller configured to acquire a temperature of the cooling water of the water jacket in the engine and, when the temperature is above a temperature threshold, control the flow rate adjuster to increase the flow rate of the cooling water supplied to the undercover cooling water passage compared to when the acquired temperature is below the temperature threshold.