Help to Identify hose out of firewall

[Dartman67]

I'm working on a buddies 1968 Imperial and as is with most old cars its a bit of exploration and guess work as not everything is the way the factory did it. There is a rubber hose that exits the firewall by the brake booster and then is just tied up in the harness and not connected to anything. I know the car has a number of vacuum actuated controls with heat and air or perhaps a drain tube - I just don't know but hope someone out there does.
Thanks in advance for taking a look

 

[volksworld]

when all else fails crawl under the dash and see where it goes? my 68 fury has a vacuum hose that comes out of that location but it's much smaller in diameter...like washer hose tube...it connects to the fitting on the manifold for the brake booster hose which has a small branch on it...it's the source that operates all the vacuum actuators for the heater and a/c and should be attached to a multi port vacuum harness plug before heading to the heater control and the actuators...at least that is what it does on mine...imperial or ATC could be completely different...

 

[DbnGrnGiant]

The Vacuum fitting on the manifold should have two ports, one for brake booster, other for the park brake release. Line from the fitting goes to a small vacuum reservoir tank. The line you have tied up comes out of the tank and to the park brake release/reverse light switch at the base of the steering column. This switch is made of plastic and prone to breaking. I have capped off the vacuum fitting until I can repair my switch. I'll get some pictures of the tank and switch next time I'm out in the Garage.

 

[Dartman67]

I knew someone would have the answer - Thanks. I have not yet gotten under the dash as I'm working on other things while waiting for material to have the front seat done. Once I pull the seat I will attack my dash issues - emergency brake not operating, intermittent operation of windshield wiper, turn signal cam broken - - -