>anyone have an 1984 Vanagon owners manual?

for a new never-used one, try these folks ....

Out-of-Print Service/Owners Manuals
Volkswagen United States          if it's still available,
they'll send
1-800-544-8021                    it to you. $16 each.
if you want a Camper Supplement, be sure to ask for it. no extra
charge, but they won't send it if you don't ask!

>I have 4 sliding controls for the heat in my 84 Vanagon wagon
and also an overhead set-up with a switch between >2
knobs ---anyone have an idea on what is what ?

the knob on the left is teh "fan switch". sohoudl be three
speeds. if this knob is off completely, the a/c will not work.
the knob on the right is the "temperature control switch". rotate
to the right for cooler. note that if this knob is even slightly
'on', the radiator fan is likely to run ... so you get in and
crank up, thinking the a/c is off, but the radiator fan starts
running immediately. this is because the a/c condensor is part of
the radiator and is cooled by the same radiator fan. :
the switch in the middle is "air volume preselect". (!?).
quote" with this switch, you can preselect blower motor (rpm)
speeds. depress right half of rocker switch for high speed.
depress left half of rocker switch for low speed. the operation
of switch A (left knob) and B (rocker switch) result in a
six-speed air volume control combination."
it goes on to say ...
"operating hints.
comfort cooling.
- turn fan switch A (left knob) to speed setting "1" or "2"
- depress left half of rocker switch B.
- turn temperature control switch C (right knob) to desired
position
- adjust air outlet vents as desired.
maximum cooling.
- turn fan switch A (left knob) to extreme right.
- depress right half of rocker switch B.
- turn temperature control switch to extreme right.
adjust air outlet vents as desired.

>Then there is another switch beneath the rear window
defogger---looks like a glowplug symbol on it----that one >needs
identification also.

here you are probably running into the DPO syndrome. that's
Dreaded Previous Owner. :)
someone likely got a glow plug or some other switch out of a
junkyard and put it in the dash ... to run some extra added
attraction. like fog lights or some electric heater or something.
the idea likely would have been that a glow plug switch could
handle a lot of amps. which is a bad idea, since you really
should wire those types of accessories with a relay.

hope it helps. good luck!
joel