Need Help on A/C Controller Vacum Line Routing

[Bob Mansker <oscargum@datasync.com>]

Someone before me has been messing with the Vacum lines for the Climate
control on my 87 5KQ.
Here is the problem..... I have a copy of the Bently 87.127 vacum layout.
Vacum line #1 (red) goes two a splitter & one side goes to the
inside/outside air value.  The other goes to the Heater Value.  Not so on my
Audi..... The #1 (red) vacum hose goes up to the air intake on top of the
dash.  There is another port with no vacum hose on it.  Why does the Temp
sensor on top of the dash need Vacum??  
Can anyone help?
Thanks,
Bob