edmontondown 发表于 2013-1-2 23:56 % x# S5 `5 g( L3 S* T# ~ xyes, may have something fell down on the other end of the hood vent
( n3 F+ ]9 y" V( ^/ K5 D0 c5 fAt 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.