Kitchen Extractor Fan Blowing The Wrong Way . In the main swapping the supply wires will not change the direction it is nearly always something. With a blocked duct, the fan may spin, but there would be no air movement. 4 6 8" Inline Rotating Duct Fan Booster Exhaust Air Extractor from www.ebay.co.uk It also depends strongly on the fan’s intended use as well. The rear of the motor has 4 terminals with only 3 in use (l,n,e). The problem is, i have no idea where the fuse is.