A cooling system for a vehicle includes a heat exchanger unit which cools a heat medium by heat exchange with air, a fan which sends air to flow through the heat exchanger unit, and a shutter which switches between an opening and a closing of a pathway through which air flows from an outside toward the heat exchanger unit. A control unit controls operations of the fan and the shutter, an index acquisition unit acquires a heat radiation index showing a magnitude of a radiation amount required in the heat exchanger unit, and a fixing determination unit determines whether the shutter is closed and fixed. The control unit performs a control in which the fan is driven while the shutter is closed, when the heat radiation index is equal to or lower than a predetermined threshold.