On Aug 28, 8:33*pm, Jon Danniken .

I can hear the flap fall back into place immediately after the fan is
turned off, and I can also hear the flap fall back into place during
times of a strong wind blowing outside (I'm guessing due to Bernouli's
principle).

Jon

Sure, strong winds causing a flap makes sense. I used to have that
before the new vent was installed.
But now I'm getting flaps in moderate and slight breezes, which where
I live is very common.