A method of operating a cooling fan in a cooling system for a vehicle includes
determining a required speed of the cooling fan. First and second signals are provided
to a motor controller operatively connected to a motor having a rotatable portion
connected to the cooling fan. The first signal coarsely controls a rotational speed
of the motor by adjusting a voltage level provided to the motor and the second
signal finely controls the rotational speed of the motor by pulse width modulation
so that the cooling fan rotates at the required speed.
