Shouldn't be 4wd vacuum - all of those hoses are in the engine compartment, not under the dash.
I have yet to go into my heater system and get it working again, but from my preliminary reading up on the whole system there is one control that operates off vacuum while all the rest are cable operated(can't remember which one at the moment). The hard vacuum lines in the picture may be part of that. There is enough stuff on mine that has been bypassed, altered, or removed that I haven't come across that exact fitting yet - but I'm still exploring and finding things to reconnect properly.
Merritt Island, FL
When a person asks you for advice, they don't want advice. They want corroboration
Heater isn't working either... (the list gets longer and longer... ) But, I think the black and green tubes are part of the heating system. Does anyone know what the little "button" on the third picture does? Should it be hooked to something?
How about the first picture? Anyone have any ideas? This wire/connection is just hanging down behind the heater control unit.
That's exactly where picture #3 goes... great. I get to pull out the whole heater control unit and see if I can reconnect. It looks like it controls the heat, defrost, vent...
Still wondering what the top picture connects to... Any help or anyone have a guess? Seriously, a guess would be closer to where I am now... I have searched under the dash for a place to connect it... but can't find anything.
There are a lot of wires that were put in case that option was ever installed. You will even find wire to the non-existent AC unit under the hood.
The Closest I have found to it so far is for the Rear window defogger. But the colors I have list are incorrect from what you have there. The other one that looks close would be the Emmision Maintenance timer, which most of us disconnected at one time to get the light to go off on the dash. Gonna take a look at mine.
On my 89 that isn't the Emission timer either. The one you have is bigger.
I'm basing my defogger guess on the Wiring diagrams for 87-90 they show a plug similar to that, but no scale. They list the wires as BR, BR/WT, BL. Also according to this the other half of that would be above the parking brake handle.