edmontondown 发表于 2013-1-2 23:56 9 }8 r' d( c! W/ f1 I; ]yes, may have something fell down on the other end of the hood vent
) Z2 n/ g# }0 [/ f- iAt 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.