What is this line?

[Ben's Z]

I found this line going in to my fire wall broke off. I think I found the other end, went to something A/C related. Going to be trying to get the AC to freeze me out and want to make sure I cross my I's and dot my T's.

Unknown line.bmp

[FastWoman]

That goes to the HVAC mode selector switch (e.g. off, vent, AC, heat, bi-level, etc.). That switch sends vacuum to the various actuators in your HVAC system, opening and closing doors, turning on and off your heater core flow, etc. It's supplied by the two magnet valves on the passenger side fender, which are connected to the milky white plastic vacuum reservoir (football shaped). You should find out all about it in the factory service manual. BTW, if your vacuum selector switch leaks, also see a thread of mine about the vacuum switch, in which I describe how to take it apart and clean it up.