There are two types of range vents.. One has the flapper OUTSIDE the motor home,, the other INSIDE.. The inside one that I have the flapper is made of a material that will not make noise when it flaps so I would not know if it's flapping or not
The outside ones I have seen the flapper is moderatly hard plastic and will indeed make noise.
On those there are two turn locks, one on either side of the flapper... Turn them and the flapper is locked closed. Will not flap.. DO NOT forget to unlock when parked.
(Project of the month on this rig was fixing the )[email protected]
(#$* Range hood.... I have the interior flapper type... With the new fan motor I know it flaps.