"220V Cooling Fan" of different tone, while the fan is running in addition to the wind outside there are other sound. This is the fan has different sound, abnormal sound may be caused by a foreign body or bearing deformation, as well as improper assembly or collision, or motor uneven winding resistance, resulting in loose, may produce different tone; "220V Cooling Fan" of life: by motor life, use of the environment, power supply and other factors consisting of fan vibrations: If "220V Cooling Fan" rotor. physical centroid rotation center of the rotor shaft axis is not the same, it will cause rotor imbalance, will produce vibration!