Under the hood, passengers side, on top of the fan duct, next to the
firewall, there is a little "vaccum pot" looking thingy. It appears to
control a damper in the duct. There is a little white tube coming from
the vaccum thingy and it goes through the firewall; I don't know where
to. The little tube is broke. My A/C works fine as far as I can tell.
What does the vaccum thing do?