PURPOSE: To obtain a comfortable drive condition even under a hot weather by providing a change-over circuit for reversing the rotating direction of a motor driven cooling fan in accordance with a previously set condition so that change the blowing direction of not blast produced from a radiator.

CONSTITUTION: In a water-cooled engine in which a motor driven cooling fan 8 is incorporated in a radiator 9, a change-over circuit 12 which can change the rotating direction of the fan 8 between normal and reverse directions in accordance with a previously set driving condition is connected to a drive system for the cooling fan 8. With this arrangement, during low speed running, or during the repetitions of low speed running and stopping, the rotating direction of the cooling fan 8 is reversed in accordance with the previously set drive condition such as a running speed, so as to blow hot blast produced from the radiator 9, forward while ensuring a predetermined engine performance, thereby it is possible to obtain a comfortable drive condition.