edmontondown 发表于 2013-1-2 23:56 4 B2 s2 h$ r. @& }' L3 [/ D7 syes, may have something fell down on the other end of the hood vent
2 v/ k! B- R3 ZAt 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.