edmontondown 发表于 2013-1-2 23:56 + Q; _# |# x* o% {% t5 vyes, may have something fell down on the other end of the hood vent
, x1 B' C+ [; y2 a% h! ~( L8 U3 kAt 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.