"AC Axial Fan" to note that for the suction fan blades also need to check, of course, first unplug the thread around the connection. Check blades for cracks, and if there are cracks if not promptly replaced, "AC Axial Fan" due to the use of force action blades easily fly out, in addition to promoting the wind wheel to rotate at a certain speed, to see if there what is unusual, including whether the rotation will suddenly encounter much resistance, if the rotation time will generate noise and so on. Multiple parts and machinery inside the damper is connected to the office connected to the also very prone to loosening the screw off if there should even be replaced. "AC Axial Fan" because the blades exposed when used long-term, it is easily contaminated dust. Once the thick dust on the fan, exhaust ventilation capacity will be reduced, and power capability is greatly enhanced.