When the "Mini Air Cooling Fan" normal operation, with the direction of the impeller rotor is in the same direction, an exception occurs when the fluid direction, the rotor is abnormal vibration. So this is the reason causing the fan rotating stall. "Mini Air Cooling Fan" dynamic stress increases the blade may cause blade breakage, so the absolute reference system from outside the impeller, the stall area or rotate in the direction of rotation of the impeller, causing the mechanism of rotating stall, to prevent "Mini Air Cooling Fan"unexpected failure resulting in unnecessary losses, we must make improvements from the design. Thus fundamental to dispel criticism, to change nature.