[200q20v] Re: [200q20v]another defrost problem

[hah3 at mindspring.com]

The a/c compressor has a safety shutoff below about 35 degF ambient, becaus=
e if it ran at lower temperatures the evaporator coils might ice up, freeze=
, and damage themselves which would be a bad thing. So below around 37 degF=
 you aren\'t getting air conditioning any more...this means that unless the=
 air coming out the defroster vent is fairly hot, it won\'t be capable of a=
bsorbing much moisture from the windshield especially if it is humid out. M=
ore interior fogginess is sort of normal in these conditions...more so if t=
he spring on the recirc flap in front of the glovebox is broken/unattached.

However, your curvy-road induced behavior does suggest a clogged drain some=
where. There is one from a pan under the evaporator assembly that you can s=
ee from under the car, behind the RF wheel. Probably also a sunroof drain i=
n the area...and if you remove the black plenum cover (have to take off the=
 wiper arms) you may find a clogged drain there as well, there is one outbo=
ard just in front of the evaporator box. Leaves and pine needles like to ge=
t under here and stay. Judicious poking with something like a straightened =
coathanger might prove beneficial.

HTH
Henry Harper
http://www.mindspring.com/~hah3  hah at alumni.rice.edu
1991 200 quattro, 114k, aaah, quattro weather is here!
1988 GTI 16v, 223k, mom\'s beater for a couple weeks

Tresturbos at aol.com wrote:
> >

Interesting that this should come up, as I was going to ask about this kind
of problem as well.  Only in my case, the defrost works fine for long perio=
ds
of time, only to completely fog the windows after driving through a curvy
section of road just a 1/2 mile from home.  It fogs up quickly, and so
extensively that if I didn\'t roll down all the windows, I wouldn\'t be abl=
e to
see my way home! One time, when I left the windows closed, I parked on the
side of the road and waited about 10 minutes for it to even partially clear
up.

I\'m thinking that in the curves, water must be sloshing into an opening
somewhere in the ventilation path. Not knowing how the system works, I
haven\'t a clue what to look for.  BTW, every time this has happened, the
outside temperature has been sub 37-40 degrees(f).

Any recommendations or advice would be appreciated.