Axial cooling fan used "220V AC Cooling Fan" happened, we must stop to check, can not continue to run the boot, otherwise it will cause great damage to the fan, you can check the fan flow is not a long time in a stall condition working, air pressure pulsation amplitude increased significantly, "220V AC Cooling Fan" blade resonance damaged; the body's own body is no problem, start the design is reasonable; stay hidden during installation, such as unbalanced shaft or coupling well, leading to fan vibration, bearings, couplings easily damaged; if none of these reasons is that it is not consider "220V AC Cooling Fan" fan selection inappropriate.