Vacuum line at firewall snapped

Where does the snap black hard plastic vacuum line going into firewall connect to? I've removed and checked the control switch and no connection there. I know the vacuum lines from the control switch go to the actuators. The harness wiring and snapped black plastic vacuum line at the firewalll grommet move up and disappear somewhere into the dashboard. Does anyone know where vacuum line goes and what it connects to? And can it be access without ripping out the dashboard?

To my question on the black hard plastic vacuum line. I believe that vacuum line controls the Heater/AC vents. I am only getting Heat/AC at the Defoster and Floor vents, but nothing from the dash vents.

The line should connect directly to the rotary ported selector on the heat-A/C controls.

I doublecheck but I did not see the hard black plastic vacuum line connected to the Rotary Ported Selector/ Heater-A/C Controls. Those lines are various colors and followed them to the actuators. I'm thinking when the Vac line goes up inside the firewall/dashboard perhaps it connects to a module manifold but it's literally impossible to find. I appreciate the information Bowtie. What I would like to do is eliminate it and run a soft new vacuum line from within the engine Tee and off to whatever it hooks up to.

After reading the Blue Bowtie's reply over, I went ahead and search the net again and again and found a vacuum diagram which makes him semi-correct.

Rather than connected directly to the Rotary Ported Selector/ Heater/AC Controls, the hard plastic vacuum line ( vacuum source ) through firewall connects to Black/gray In- Line Vacuum Hose Connector which connects to the Vacuum Harness which connects to the Heater/AC Control Assembly.

I went ahead and attached the diagram for anyone having the same issue.
Thank you Bowtie for making me look further.

Perhaps I was over generalizing. I meant that there were no devices between the vacuum source and the ported selector. Similarly, the I/P fuse panel is connected "directly" to the battery with no switches, relays, or controls between the battery and fuse panel bus. However, there is the main bulkhead connector, battery node, and fuse links.

Thanks for posting the full diagram for clarity (and posterity). The hard nylon line is more difficult to find in smaller diameters than rubber vacuum hose, but can be replaced with clear/natural colored nylon line commonly used for lubrication and pneumatic lines on industrial equipment. Don't use polyethylene tube since it will melt at a low temperature - Stick with nylon.

http://ph.parker.com/us/17573/en/high-strength-nylon-tubing-semi-rigid-ntna-series

http://www.usplastic.com/catalog/item.aspx?sku=58529&gclid=EAIaIQobChMI7oKImLPl1AIVyyWBCh0u6wPgEAUYAiAB EgJXh_D_BwE

Once again thank you Blue Bowtie! I went to the junkyard and saw a vehicle like mine. I followed the vacuum source line and I want to confirm that you are correct, "no devices between the vacuum source and the ported selector". The hard black nylon vacuum line connects directly to the black and gray striped vacuum line with a connector holding them together.

I repaired my vacuum line just like the diagram and the vehicle at the junkyard and happy to say that I am now getting AC air out of the dash vents and my selector switch works perfectly.

Thank you for the recommended source where to locate the ideal vacuum lines!