I've got an '89 and had it for many years. I was always 'ticked' re the
heater controls - particular the defogger. I could never figure out how
to turn it on 'normally'. Well today I finally figured it out, accidentally
of course. Possibly there are other out there like myself who find the controls
a bit mysterious.
To wit. When the temperature control is turned up full tilt, 'then' will
the hot air come out through the window vents big time! Otherwise always
just dribbles (not talking about the defog position on the pushbuttons).
Hope this helps others like myself....