edmontondown 发表于 2013-1-2 23:56 1 J$ b7 d6 w% X7 N2 V6 vyes, may have something fell down on the other end of the hood vent
) p- m' g. u; y) w6 @/ _4 y0 YAt 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.