For whatever reason I continue to battle foggy windows in my van on the inside. This has been a constant issue with my van since I bought it in 2010. I have tried window cleaner a mix of vinegar and water and such and while that stuff cleans the inside window great, it won’t deter the fogging. Any suggestions on a mixture of something I clean the inside window with that will deter or reduce the fogging.
Any leak or stopped up drain keeping the carpet wet? Do you keep the a/c running in winter? That + heat usually keeps thing pretty fog-free. Anyone smoke in it?
What make/model? Whereabouts do you live?
Carpet’s dry, don’t use AC ever, no smoker now but may have been with previous owner, 2002 Kia Sedona mina van…Indiana…
Do you mean a haze in the winter from moisture condensation or the haze that forms over time no matter the weather? Moisture fogging indicates that the front window defogger is not working properly. The other haze is from the plasticizers in your dash board. Any time the top of the dashboard gets hot, it will outgas. You could get a window screen at an auto parts or big box store and deploy it whenever you leave the van in the sun. Or just keep cleaning. It will slow down eventually.
If you don’t use your a/c the windows will fog. Why not use it?
If your “fog” is actually moisture, you may have a small water leak (in the windshield seal or elsewhere) that’s letting rainwater into the van in small enough quantities that the carpet doesn’t get wet but it condenses on the windshield. Also, have your AC drain hoses blown out in case they’re clogged and water is collecting in the AC drain pan.
If the fog smears when you wipe it, you may have a leaking heater core inside the dashboard.
That will let water and antifreeze into the cabin, where it evaporates and condenses onto the windshield.
If your heater control is set on recirculate that will cause windows to steam up. Also, on most cars using the defrost setting will turn on the a/c some. If you have the controls set for floor or dash, turn on the a/c and just use your temp control to regulate the heat.
So there is no magical stuff out there I can wipe on the windshield that will keep the fog from forming? We can put a man on the moon but haven’t come up with some spray or such to solve this problem…ugh… 
“there is no magical stuff out there I can wipe on the windshield that will keep the fog from forming?”
If there is a leak in the heater core, no “magic” will help.
If there is a leak in the windshield’s seals at some point, no “magic” will help.
If you typically operate the HVAC system on the “recirculate” position, no “magic” will help.
And, if you refuse to use the A/C, no “magic” will help.
First, you have to eliminate the cause of the excess moisture inside the van before you can even consider some type of magic in a bottle.
Given the age of the car, I doubt it’s a leaking heater core, leaking windshield, or defective window defogger. But @bertrand, you have not described the problem in enough detail to know for sure which problem it is.
@jesmed - it’s a 2002, so I wouldn’t be surprised by a leak, etc.
"Given the age of the car, I doubt it's a leaking heater core, leaking windshield, or defective window defogger. But @bertrand, you have not described the problem in enough detail to know for sure which problem it is."
@jtsanders–I agree completely with your second sentence, but not with your first sentence.
Why do you think that an 11 year old Kia Sedona (a model with a much-worse-than-average reliability rating) wound not be subject to any of those problems?
Because this vehicle was purchased as a used vehicle, after at least 8 years of service (and with a possibly unknown record of maintenance on the part of the first owner), it is entirely possible that the coolant was not changed on schedule, and that the heater core is rotted-out.
A leaking heater core is a possibility. Make sure recirculate is not on, kick as much snow off your foots before you get in the car, open a rear window to let warm moisture laden air exit the vehicle,
All good comments above. It could just be though that there’s a lot of people in the car, maybe some have wet clothes, etc, and the temperature is cold so the windows fog. I think I did read somewhere that there’s been some discoveries recently on anti-fogging agents for glass. Unfortunately I can’t remember where I read it. You could try Googling I guess.
I used to have this problem when skiing, not with the car windshield, but the inside of my skiing goggles would fog. I got some relief by wiping the inside of the lens with shaving cream, then wiping it off. Here’s a link on that idea …
The first post said it was purchased in 2010, and I guessed it was new. I missed the update. Based on the 2002 model year, I would now say that anything is possible.
We still haven’t heard whether the OP is operating the HVAC in recirculate mode. That would account for the problem and is the easiest and cheapest thing to fix!
To the OP: has anybody looked at this?
I know it’s easy to hope for a “magic wipe”, but the truth is that you have a source for the moisture and in all likelihood an AC system that needs to be leak tested and, as a minimum, recharged. Somebody is going to have to look at the vehicle hands-on and determine why this is happening. We can’t do that over the internet.
If you decide to work on the vehicle yourself, we can walk you through the processes, but I didn’t see any indication f that in your posts. My recommendation is to find a reputable owner-operated shop and have them take a look.
Sorry, but there’s no magic. Only diagnosis.
RAIN-X makes a “magic wipe” anti fogging liquid that would probably work. However, don’t be surprised if you go from a foggy windshield to a ‘very wet’ windshield as all you’d be doing is masking the actual problem. I had a vehicle many years ago with this exact same problem and although RAIN-X worked, it didn’t fix the leaking heater core in the vehicle. You’ll have to apply the RAIN-X daily as well.
The OP nevert responded to questions about if he uses recirculate or why he doesn’t use the a/c. I guess he is less intrested in his problem than we are.
"Don’t use ac ever"
Guess I’m a little thick. I have not had a car in the last 20 years that did not need the ac to help in cold humid conditions. Until OP tells us he uses the ac and outside air and still has moisture problems, IMO, it’s just an exercise in futility.