edmontondown 发表于 2013-1-2 23:56 7 P" F5 f$ Z! b+ f0 o1 E" M" c8 Byes, may have something fell down on the other end of the hood vent
1 ^+ g& n9 @& m: r) P3 b q5 qAt 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.