heater and interior humidity problems

[Adam Sciortino <A.Sciortino@usa.net>]

I've got a couple problems with the climate control on my '85 5k that can no
longer be ignored now that winter is starting to arrive here in Chicago:

1) The defogging control can make interior humidity worse.
When the inside surface of the windshield is just starting to show signs of
fogging up, I'll push the defog button on the climate control panel
(previous setting is off) and soon air starts to come out of the proper
outlets at the base and sides of the windshield.  Often, the initial result
is that the windshield totally fogs over, the side window's start to steam
up as does the rear window.  It's like a cruel joke--the system does exactly
the opposite of what I want.  Then after the glass is nicely fogged over,
the windshield very slowly starts to clear up.  It first starts at the base,
just above the outlets and gradually works to clear up most of the
windshield.  Enough to start driving safely.  This process can take 15
minutes.  Sometimes it only clears more than a small oval above the outlets.
I'm forced to constantly wipe the glass with whatever is available.

What is going on?  Is there a place in the system where moisture can get
trapped and then will get pumped into the car when the defog button is
pushed on?  This problem has nagged me for the past 2 winters and has yet to
be resolved by my otherwise successful repair shop.

Any ideas?

2)  The Auto setting on the climate control no longer works.
In both A/C and heater conditions, the Auto setting no longer results in any
air flow, regardless of the temperature setting.  I've discovered a way to
get air flowing, however.  First push the defog button to get the air coming
out of the defog outlets, then push the Low or High setting buttons.  Air
then starts coming out of the dash outlets.  Sometimes for a long while,
sometimes for a short while.  When air flow does stop, it shuts down very
rapidly.  This is also what happens if I push the Auto setting:  the unit
rapidly shuts down all air flow.

Combo of 1 and 2)  In the winter it's tough getting the car comfortably
warm.
When I do get the heat to come out via the process described in 2 above, the
car usually starts to fog over.  To counteract this I switch to the defog
feature and lower the temp setting to get more dehumidifying effect.  This
lowers the interior temp a lot by the time the windshield is clear enough to
drive (meanwhile it's around 14 deg. Fahrenheit outside).  Then I try to get
just a little heat, but then the process starts all over again.  It is a
cold and foggy cycle.

Thank you for any ideas on the cause and possible fixes for these problems.

-Adam
'85 5ks (mine, manual, 182k)
'89 200TQ (dad's, 140k)