I did a search but could not find an answer to this: Our newly bought used 98 v70 XC windows fog up badly anytime there is moisture outside and we have the windows closed. Usually in the mornings (cool) and last Wednesday night driving home from San Diego by myself. When the defroster is turned on the fogging only gets worse. Running the aircon when it is cold outside helps but doesn't get rid of all the moisture in the cabin. It seems to be worse on the passenger side including all the way back on the right side windows. Running the fan on high doesn't seem to help and the defrost mode makes the fogging get worse.
Also, there seems to be water (?) vapor coming out of the vents on the passenger side vents, both in the morning drive to work and during moist evenings. It looks like smoke but isn't. This is really a driving hazard as we cannot see out the windows clearly. What is our problem?
Thanks.

Get a leak-down check from the service guys (local of course) takes 5 minutes and that will tell you for sure if there is a leak in the cooling system in its entirety.

Regards'
Jim

Check theeasy stuff first. The "smoke" from the AC vents sounds fine - this is frequently seen in high humidity situations if teh AC is working well. It also suggests that the AC is well charged and not leaking, a good thing ;-) It certainly suggests that there is nothing wrong with the infamous evaporator, and the evaporator leak would only let freon excape, it wouldn't create any moisture issue (no water inside it). I would next look for water collecting somewhere in the car, particularly under the carpets wehre you don't see it. Even waater collecting under trunk carpets would create this situation. Could easily be from a leak in sunroof (blocked drain) or AC drain blocked and escaping into interrior. You don't mention smell or greasy feel, and I would expect some of each if the heater core was leaking, since it would be allowing anti-freze to escape into the interior. Anti-freeze has a sort of sweet smell. Can you wipe the interior glass clean pretty easily? That is where the anti-freeze would be most noticeable if leak is significant, and wiping leaves greasy streaks.
Best of luck,
Mike
--
Mike Sullivan ('91 745 (171k), '93 965 (147k), '95 855T (60k), '98 V70XC (78k). Past Volvo's: '85 744 (256k), '86 245 (165k), '86 245 (195k), '88 745 (208k).

A leaky heater core is typically the problem if running the fan
causes it to fog worse (the air flow throught the vents passes through
the heater core). The heater core could be leaking coolant/moisture
into the air supply and that fogs the windows. I would think it would
also have a slightly sweet smell.

You can go to google.com and search on:

heater core leak foggy window

to see some general info on this.

Heater core failure is not reported very often for the 70 series
so it could be something else. Maybe a leaky heater hose connection.
A plugged drain for the AC could also cause this (I guess) or anything
that could cause water to backup or condensation to not drain properly.

I'm sure there will be other posts with other things to check. So hang
in there.

Are you sure it is water and not antifreeze? Your description sounds more indicative of a leaking evaporator than anything else.


Rule 308

Thanks, guys. At this point I have no clue as to what is happening. Smell? Maybe a slight sweet smell....hard to say, really.
Yes, the window seems to streak a bit instead of cleaning off as would condensation.
Next call will be to Nikko at Autohaus Bavaria to set up a checkup.