edmontondown 发表于 2013-1-2 23:56 " s D* [4 B9 ?# j5 oyes, may have something fell down on the other end of the hood vent
$ D1 ?1 ^3 n6 Z1 S9 }6 B* R3 ~At 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.