This video describes a design flaw in nearly all bathroom exhaust fans. The built in flapper valve is not heavy enough to stay closed when winds are even mild. This causes the valve to be slightly open all the time during winds. Then when the wind changes direction the valve will slam shut and make an irritating noise. This video shows how to fix it for cheap in 10 minutes.
0:00 Intro
0:20 Remove cover and fan motor
1:02 Description of poor design
2:29 (Not so) Scientific demo and how to fix the rattle problem
4:18 Implementing the fix
5:44 Improving the fix
6:06 Wrap up