A cooling system constructed to cool down an accumulator mounted on a motor vehicle is herein presented. The cooling system sequentially controls an air blower to restrict the air blow to the accumulator, controls the air blow mode switchover module to switch over the active air blow mode after restriction of the air blow to the accumulator, and controls the air blower to release the restriction of the air blow to the accumulator after the switchover of the active air blow mode by the air blow mode switchover module.