jerry joseph

Had something similar happen to me a few months ago
Before sunrise,on my way to the local Starbuks,I got caught in a steady tropical shower..and extremely quickly the windows fogged up so fast
Fortunately I had pulled into the parking lot
However,once parked,no amount of AC/Heat/ventilation would make the 'window' fog go away...
Only thing that restored some visibility,was to use the windshield wipers
I was just a few blocks away,on mostly empty roads,so I made my way back no problem..but nevertheless...
....first EVER time using the inside hot air window-directed ventilation did NOT HELP at all
The only explanation I could think of was that occasionally wiping the windows with a microfiber that had some Carnauba wax residue had left a light film that was prone to fogging
Never happened again,but I would love to understand what happened
I understand we are in the "Pen"...nevertheless driving in "foggy"conditions is one of the scariest possibilities I know of..and is most definitely NOT A JOKING MATTER
So,I thank you as well for any useful comments

carlos50

The car is new to me but had a major service a few months ago, the service invoice isn't detailed with parts so I can't say if it was changed or not.

Will speak to the indy (a Porsche racing team) who did the service to find out if it was done?

carlos50

Correction, yes the pollen filter was changed 6 months ago and only a few thousand miles ago according to the service invoice.

deilenberger

When you say the floors are dry - did you pull up the carpet to see? There is about 1.5" of foam beneath the carpet, and if one of the sunroof drains is plugged up, it can leak down inside the A-pillar, through the fuse box, then down behind the kickpanel and never appear or be visible. You may well find the foam rubber soaked, even if the carpet feels dry. BTDT. Cleaning the sunroof vents fixed the fogging issue I had, and the floor has stayed perfectly dry (under the carpet) since then.

It's easy enough to check. Find some sort of hooked tool. Slide it under the door sill and rotate the hook downward. Pull toward the center of the truck. The carpet edge will come out from under the door sill. You can then see and feel the foam rubber. A plugged AC drain can have the same problem.. it can leak behind the carpeting and never be visible to you.

The big clue is the fogging.. something has a lot of water in your P!G, based on my experience, first place I'd look is under the carpeting.

BTW - once you learn to do this, you can do this check in seconds. I have frequently, like after hurricane Sandy roared through here.. mine has remained dry.

On another forum I have a step by step photo DIY on clearing the sunroof drains (and how to find out if they're the cause of a wet floor.) Found it: http://www.renntech.org/forums/topic...ssenger-floor/

Have fun.

PorscheTX928

I have a similar issue with my 08 Cayenne S. I have not had it very long, and it does not get driven all that much. Interior is dry(carpets), and the AC seems to work very well. But ever since I have owned it, the vents under the front windshield stay on all the time, and they always cause condensation along the bottom edge of the windshield. When it rains, it is really bad...where I have to use wipers to clear windshield. It is very annoying and even when I put bottom or dash vents only, the windshield always seems to get air and always develops the condensation...I thought this was normal, but from the sounds of things, I guess it is not.

dasams

Are you saying that you blow cold air on the bottom of the windshield and that it causes condensation on the outside? If that's what you are seeing, it's perfectly normal and caused by the outside air adjacent to the windshield dropping below the dew point. Why can't you turn off the air to the windshield so that it's only directed at the interior vents and/or the floor vents?

touareg

I usually make sure the car is on re-circ, don't allow fresh air from outside (as you are sucking in more humid air and it is harder for the car to keep up)

Then blow the vents to the windshield, sides and all is fine.

I live in a humid area, and that usually does it for me, keep it around 71F most of the time.

If it was winter, I would say you have a leaky heater core.

PorscheTX928

Dasams: Yes, it is on the outside which is really weird because it is 90 degrees outside. I can not turn off the defroster vents for some reason. If i hit the center vent or floor vent buttons, air still comes out the windshield vents and causes my foggy windshield. It is worse at center bottom, but at night, or when raining, it is really bad. Perhaps there is something blocking the vent? There are no strange noises, but I will look into this more carefully. I know now that this is not normal, so I can begin with the simple things (Vent flap blocked, changing cabin filter).

69gaugeman

Not weird at all. Any moisture in the air will condense on a colder surface. That's why your margarita sweats on the patio.

It sounds like the defroster servo is not working. Connect durametric or Vagcom and look at the HVAC controller. It will give you clues...

TurboTodd

I have had the same thing happen occasionally on my 2009 Cayenne S. I am in the middle of a cross country trip.
Im in Columbus GA now and had huge rains last night. Dam pig fogged up like crazy. Bout the only thing I could do was to crank up the heat. Not fun in hot and humid weather. Not fun on unfamiliar roads in heavy traffic. I understand the physics. Cold air on the warmer humid windshield. I get it.

I can tell you I have other cars that never fog up. Not happy with the pig right now. I was thinking about another Cayenne purchase, a turbo this time.
Now Im going to look at a ML63.

PorscheTX928

Im glad someone else is experiencing the problem. I guess that at least means it might be a more common issue than some freak occurrence. Todd-my suggestions to help until we can figure it out are: set front and down vents only as this partially helps as others mentioned. Also, I have a small towel I throw in between dash and windshield which does help a lot. it keeps the really cold air from hitting the windshield directly and minimizes the condensation and some of the fogging.

I have other issues with the Cayenne at the moment so the fogging is the least of my worries, but if anyone has similar issues or input, Id appreciate it...I will try to read values on defrost controller when I can, but I really think it might either be a blocked vent flap since even with the vents closed to windshield this happens quite easily.

I have some fuel pump/filter issues im working on right now, although this is a slow process because it's too hot to do anything in Texas right now, and unfortunately, my garage is filled with other toys at the moment.

TurboTodd

I did give the vent down method a go It was not humid so probably not a good day to test.
What I did find is that in the with the vents set to down the air in the back stops.
Not good when your wife is setting in back.

The manual says for best performance keep in auto. Of course thats not the case.

wrinkledpants

Condensation on the outside of the glass is from cold AC blowing on it. This isn't car-specific, per se, as vapor will condense on anything that's colder than the dew point.

If you're getting interior windows fogging up - then you have an issue. Greasy interior windows will make it easier for water to cling to, so try clearing your windows so there is zero haze on them. Otherwise, my guess is you have an issue with the AC system or a plugged AC drip line.

The only time I get condensation on the inside of the CTT, or any car for that matter, is when it's loaded with with skiers and damp ski gear. Even then, it only takes a few minutes for the car to get most of the glass clear. I've never had condensation just from driving in rain.