Back when my dad purchased his 92 s10 it had a ton of vacuum leaks and the air flow was only on top and bottom. I replaced every rubber line in the engine bay. Already checked the rubber lines at the t in the engine compartment etc. they are Fine. I just plugged off the line then to fix the vacuum leak as the idle was jumpy but now i wanna fix the issue. Before bypassing it heard a faint hiss coming out of the dash.



Any hose diagrams available for the dash? Im not sure exactly where that line runs too. Or where the door is that redirects the flow etc. I know theres a bunch of vacuum lines that run into the selector switch etc. No leak found there. (or at least where it plugs into the selector)

Ive tried searching for the last hour. Everybody only says check the hoses in the engine bay,as i already have. Nothign has been said about whats actually in the dash and how its ran.



EDIT.

DANGET 2 more min of searching i found a diagram swartlkk posted.



posted it here if anyone else is having this issue.


thanks man for the help you give on the forums!




Can i access #9 without pulling the dash? I doubt it.

 

Not too sure about a '92 but I have a bugger of a box in the fenderwell that's .... unreal to get to.
As for the hissss, I'd assume the tubes would head to the dial in the dash. Get under or take the lower panels off to have a better look. Look at the heater core, to & from it. To & from the back of the dash dial.

I'm just tossing out ideas that perhaps you may not have thought of. Different perspective/3rd party sort of thing.

 

I had the same problem

my heater control was leaking and i had a hisss from there
I played around with it and my vents started to work again
and the hissss went away

 

the heater controls might be leaking itself. and yes you can access number 9 without taking anything apart.