"220V Cooling Fan" speed resolution together by the motor inside the coil turns, operating voltage, the number of fan blades, angle, height, diameter and bearing system. Speed and quality is not necessarily a fan of contact. "220V Cooling Fan" Manufacturers speed through the internal speed signal can be measured, the measurement can be performed via the external. Followed by the use of conditions and changes in ambient temperature, fan speed sometimes is not the same need to meet their needs. Some manufacturers, especially planning out to recuperate "220V Cooling Fan" speed cooling fan, two points and take the initiative to hand. Manual is designed to allow users to use low speed in the winter to get a low noise, high-speed summer terrain made good use of the cooling effect.