vacuum leak in heater??

[jonboy]

hi
the controls for the heater on my vt dont seem to be working properly.
when i rotate the dial to set it to windscreen or feet/windscreen it seem to loose vacuum???
were could it be loosing vaccum from? its like theres not enuff air or something and the more i rotate the dial i loose it on the other settings to??
i have pulled damnd near the whole dash out so any imput is good

[Claudy]

Think there's a vacuum canister somewhere so one of those vacuum lines could be broken

[jonboy]

hi
i took the cover of the motor (v8) and theres a hose coming of the throttle body and goes to the drivers side valve cover, it has come out? it appears to have just been siliconed there? what is the correct way to reinstal?
also there is a water hose above the thermostat that has a gismo with black vacuum line coming out the botom of it. it has a solinoid thing with a cable that can open and close it. its quite rusty and water is dripping out of it.
would either of these things be my vacuum leak?

[jonboy]

by vacuum canister do you mean like what vn-vs hade under the passendgers front guard? kind of a ball looking thing?