edmontondown 发表于 2013-1-2 23:56 - w6 n' c8 L6 Y ^6 H! Q& g6 h* vyes, may have something fell down on the other end of the hood vent
; u: {+ s J1 V3 o8 g- g/ L9 dAt the other end(outside) of the vent duct, there is usually a metal cover for the opening, it can swing up and down and if it is a windy day, it will be blown swinging, thus making a kind of banging noise.