Window fogging

Mike_Buckham at Mike_Buckham at
Thu Dec 12 16:18:23 EST 2002

I got this with my '86 100q also. I couldn't smell the coolant either until
one day I noticed a pool of water in the passenger footwell. Initially
there was a tiny hole in the heater matrix but it grew until it got big
enough to leak coolant instead of just evaporating and then condensing all
over the windscreen (especially in winter). I removed the heater matrix and
fixed it by clamping the leak and then soldering a piece of metal over the
hole. This worked a treat. So basically, even if you can't smell the
coolant, there may still be a coolant leak.

Cheers, Mike.
'86 100 q
'89 200 qt
('96 TVR Griffith 500)
('00 Triumph Sprint ST)

                    Eyvind Spangen
                    <eyvind.spangen@       To:     quattro at
          >               cc:
                    Sent by:               Subject:     Window fogging
                    quattro-admin at au

                    12/12/2002 10:56

Now in the winter, the windows in my '86 100q is fogging. I have to
keep the fan on a high setting and defrost, and even then, the
windshield is fogging. The side windows are somewhat better, but the
rear window will be foggy if I don't use the defroster.

This is an Euro model, no AC, so no recirculation flap that can
break/jam. The coolant level is stable and I can't smell any coolant
inside the car. I have cleaned the air intake under the plastic cover.

I've tried cleaning the windows with alcohol, didn't help. Tried some
"Rain-X" treatment that should reduce fogging - it helped somewhat,
but not much.

I've checked under the carpets - dry.. I've tried driving with a
window cracked open - no difference.

Any good tips?

E. Spangen
'86 Audi 100 2.2 CS quattro

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