edmontondown 发表于 2013-1-2 23:56 6 Z, i' q- `6 U/ t% Y
yes, may have something fell down on the other end of the hood vent
. k% O. u- [* }5 `% X" CAt 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.