Vacuum line question

["aaron_t_graham" <aaron_t_graham@xxxx>]

There's a lone vacuum line that comes into the engine from the side of
the engine compartment -- toward the back, on the left side. It's
quite lonely back in that part of the engine compartment, so it's easy
to see which line I'm talking about.

If I have this line disconnected, everything still seems to work just
fine. Idle is good, acceleration is good, and all climate controls
work just like they should. My mechanic hooked it up to where he
thought it should be, and when he did that, lots of hissing noises
started coming from the A/C panel mode switch area.

So it comes down to this: when that line is hooked up, everything
works okay and the A/C mode switch hisses. When that line isn't
hooked up, everything works okay and there is no hissing.

Any ideas on this one?

Aaron
#1506