edmontondown 发表于 2013-1-2 23:56 3 k8 f& u/ w7 R* U% Y. hyes, may have something fell down on the other end of the hood vent
1 {4 L/ s/ R; p3 h6 g7 o7 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.