[V6-12v] FW: Window Fogging

[Kent McLean]

Casimiro Izquierdo wrote:
> 
> ----Forwarded Message----
> From: caig01 at yahoo.com
> To: caig01 at yahoo.com
> Sent: Wed Apr 28th, 2010 1:41 PM EDT
> Subject: Window Fogging
> 
> I am having a problem with my 1995 Audi 90S.  When the car warms up there is
> a cloud of "water vapour" that rises tthough the vents and fogs the
> windshield and the driver side window.  This "vapour cloud" leaves a film on
> the glass surface that is very difficult to clean; it smears and Windex
> clears it to some extent.  It does not seem to be burning oil, which the
> car, but it seems to be coolant.  It does not smell much like coolant, but
> the film suggests antifreeze deposit.
> 
> - What can be done to either prevent this from happening?
> - How can I completely close the vents?  I do not care about A/C or heating,
> neither work.
> 
> Any suggestions will be appreciated.

It sounds like the heater core is leaking. That fog on the windshield
is probably from the coolant drying on the it.

If you truly do not need the heat, you can bypass the leaking core.
There are two heater hoses (about 3/4" or 2cm or so) going from the
engine through the fire wall to the heater core. Follow those two
hoses back to the source on the engine block, remove them, and replace
them with a shorter (1 foot or 30cm or so) piece of heater hose, in
a U-shape, going from one outlet to the other (or rather, going from
the outlet to the inlet; but you don't have to know which is which).
This will take the heater core out of the loop. It might still fog
a little until the water in the heater core has evaporated, but it
should "fix" the problem.

If you *do* need heat, you'll have to replace the heater core. This
is a fairly inexpensive part (about US$100), but is labor intensive
to replace (up to 9 hours, depending on who you ask). You can do it
yourself; direction are on-line and in the archives.

-- 
Kent McLean
1990 V8 w/5-speed and other mods
1991 200 TQA #3, with mods
1999 A4 Avant, V6 Tiptronic
gone: '91 200 TQA x2, '94 100 S Avant, '89 200 TQ "Bad Puppy"