"24V DC Cooling Fan" Speed is of the entire control system is an important aspect, is an important function of the composition of fans, including the DC motor and stepper motor [4] in two parts. DC "24V DC Cooling Fan" is controlled by pulse width modulation achieved by reading the temperature sensor or button to adjust the value of the duty cycle of the pulse width to achieve the speed of change in the DC motor; stepper "24V DC Cooling Fan"is the electrical impulse signals into angular displacement or linear displacement of the open loop control element [5], to determine the direction of rotation and the rotation step number of the stepping motor to achieve the positioning of the fan or the orientation of the body's perception of his head by infrared sensor module.