Our brand new 30” Zephyr Breeze II range hood is fine on speeds 1 and 2, but on 3, the internal backdraft dampers rattle very loudly. These are the built-in semi-circular dampers at the top of the unit, not the damper where the exhaust leaves the house. The dampers are very thin steel.

The hood is vented straight up about 3’, hits a 90 degree elbow, and goes about 8’ sideways before exiting through the wall.

My inclination is to take the hood down and put some self-adhesive foam pads on the top of the dampers - or on whatever they are hitting - so that when the fans are on high, the dampers will still flip up but not make a loud metal on metal noise.

Has anyone faces a similar issue? Any advice?

Thanks!