How to choose 220V Cooling Fan

Visual inspection "220V Cooling Fan". The appearance of baking and plating should be uniform and bright, no cracks, bumps and scratches. Pressed about various rotary switch, it should be fixed firmly, flexible manipulation, clear pronunciation. Check all kinds of screws, there should be no loosening. Toggle "220V Cooling Fan" fan, should be easy to rotate freely, without hitting any part. Smooth nature should stop, blocking the feeling. Axial fan promotion center, its shaking volume should not more than 0.5 mm is not obvious traverse, to debug "220V Cooling Fan" motor axis and the horizontal angle range of not less than 20 degrees elevation, depression should not be less than 15 degrees.