For a full background of this problem, please refer to my original post: https://rennlist.com/forums/997-foru...-solution.html

This past week I received the "Vision Vents" mentioned in the above post and this morning I got around to installing them. Before delving into that, the "Vision Vents" seem to be pretty well made, fit nicely into the windshield vent slots and perfectly match my black interior both in color and texture. They are held in place with small spots of double-back tape which I see might me a problem down the road. Namely, because here in the Caribbean and probably the Southern States, that area of the dash gets a lot of year-round high heat and direct sunlight. Another possible issue is that the car's windshield vents area have a slight curvature and the "Vision Vents" need to conform accordingly. Given these two constraints (heat and curvature), this may put a strain on the holding power of the limited double-back tape areas.

Anyway, I presented them both into their slots without using the tape fastening and went out for a drive. So given that my A/C is always on and we have very high humidity, this causes almost immediate fogging... but it didn't happen! As an experiment I removed the passenger's side "Vision Vent" and that area immediately started to fog up.

Here's a picture of my windshield after only a 5 minute drive. You'll notice there's no fogging on the driver's side but not so on the passenger side where I had removed the "Vision Vent".




PS: To address the curvature problem I think that I might try to use my wife's hair dryer (when he leaves!) to bend the Vision Vents ever so slightly and carefully to get better fit before fastening them down.

PPS: I once again affirm that I have no interest nor compensation from the manufacturer and only provide this information as a service to my fellow forum members.

 

Do you get fogging if you turn the AC on? If you run the AC you should not have any fogged windows. AC is to be run year-round.

 

As per my original post, the problem arises from the deteriorated foam that's used to seal the different Heating/Vent/A-C duct outlets. Hence and even when my front dash vents selected, cold air always bleeds to the windshield defroster vents and therein causing fogging. To answer your question and due to our weather, my A/C is ALWAYS ON.

This is a known problem others have previously stated that they have. Up to now, at least to my knowledge and other than sealing off the windshield vents, the solution was/is to pull apart the whole dash and replace the offending foam seals... a very, very labor intensive and costly endeavor which I personally would not want to face. This alternative seems to fit the bill because of its simplicity and at a reasonable price.

 

Do you run the A/C in the recirculation mode? That should actually pull moisture from the cabin and not allow fogging. When you select defrost mode, the car does this automatically.

 

Pete, I've tried all combinations of A/C settings but there's always a bleed of cold air coming out of the windshield vents and thus the fogging due to condensation. Grant you that our year-round high humidity and temperatures further exacerbate the problem.

So far so good with these vents and whatever the cause I'm happy to have solved this most perplexing and fastidious problem.

 

It's great when you can find an inexpensive and simple solution to a problem that would be an expensive repair

 

I noticed that all along my posts I've failed to mention that the condensation/fog is on THE OUTSIDE OF THE WINDSHIELD!

Prior to the install of the "Vision Vents" I had to constantly use my wipers to clear the condensation/fog that tended to get really nasty as the humidity rose from our all too often rain and its aftermath.

 

For the outside... the AC will not resolve it. You could heat the glass or use intermittent wipers.

 

My next-to-new black Vision Vents are for sale here: https://www.planet-9.com/threads/black-vision-vents-for-porsche-987.252256/

Please delete this post if it's against the forum rules.

 

Thank you for your post my friend, you surprisingly are the only one I've seen comment on this. Thank you for the idea, I am buying a set today.

 

When the windshield temperature reaches the condensation temperature of the humid outside air, the moisture in the air begins to condense on the windshield. Either you use the wipers to remove it or you raise the temperature of the windscreen by changing outlet temperature of A/C. Another possibility is a heated windscreen, I do not know if that would be available for 997. To me it's not clear how the geometry of the A/C outlets would avoid that condensation if you do not change temperature.

Edit: If you redirect the air into the cabin, the process is delayed but you can't fight physics.