How far away must the fan be from air-conditioning systems?

The fan will need to be installed at least 1 metre from the tip of the blade to the nearest vent or air-conditioning split system. If the fans are installed any closer than this, it can cause air that is being pushed out of the vents to rock the blades back and forth.
In some cases, a noise also develops because when the fan is turned on, the constant air being pushed directly on the blade set it will cause it to make air movement sounds.