# VW Passat fogging up



## lijongtao (Dec 1, 2017)

I keep the VW really clean inside and out. I use 99.9% IPA on the glass inside so know it is clean but in this cooler weather it is terrible car at demisting the windscreen and side/rear glass. 

I know to use the AirCon to clear it but I wonder if there's anything I can apply that will make the glass less likely to fog up? If I keep it on cold it clears. The second I go to heat, because the cabins getting too cold, it fogs up again when you're driving and it becomes very dangerous. VW In Preston said to keep the AirCon on all the time. Not a brilliant idea when it is brass monkeys in winter. 

I have the RainX AntiFog stuff but haven't used it yet as i only got it today. 

Does anyone have any suggestions please?

Thank you


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## MrPassat (Mar 30, 2018)

I had the same problem but I found the best solution is to turn the air-con on but dont use auto otherwise the fans go crazy. I like the temperature around 21C, a fan speed of 2 and the air being directed to my feet and the windscreen
It seems that the auto mode directs the air to the dashboard vents with a high fan speed and that makes it feel cold.
Not ideal I know.
Maybe my technique is poor but I've always had problems with streaking when I tried anti-fogging products.


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## BrummyPete (Jun 10, 2010)

As above I had the same issue in my passats, keep the air con on and the temp around 20/21 and it will keep it clear

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## cangri (Feb 25, 2011)

There are some products that offer window fog protection. But what I found is that they don`t last much.
Try to lower the humidity in the car. You can use cat litter bags under the seats as they will absorb moisture.


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## Andyblue (Jun 20, 2017)

Moisture present in car, which the air con will act as a dehumidifier and assist to remove. Just leave the AC on and it’ll help resolve the issue... 

Worth while just doing a double check to make sure all your carpets are dry...


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## lijongtao (Dec 1, 2017)

Checked the carpets today and they're all good. I am convinced this is the reason the previous owner sold is as I have never experienced this kind of problem with any other car I've had, be it BMW, Volvo, Citroen etc I've tried the bags to dehumidify, I've even put the home one in and **** the doors and left it on. Seals are OK too. It is just a horendous car for fogging up. So will try to keep the AC on and the temp at 69-71. 

Will I use noticbly more fuel with the AC on all the time? Also, thanks for the replied guys, much appreciated


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## MrPassat (Mar 30, 2018)

I don't notice any difference in fuel economy when the air con is on.
I agree, the passat does fog up more than many other cars.
Strangely enough the outside temperature seems to affect my economy a lot, it really drops when it's cold.


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## Andyblue (Jun 20, 2017)

lijongtao said:


> .
> 
> Will I use noticbly more fuel with the AC on all the time? Also, thanks for the replied guys, much appreciated


No, not really noticed any difference with the AC on with mpg.


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## minimadmotorman (Mar 18, 2012)

Seems really common in VW/Audi. I keep a reusable dehumidifier bag in all my cars, seems to keep it at bay.


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## Fordbunny (May 15, 2019)

Hi. My daughters Vauxhall Corsa D is terrible for fogging up. Tried all manner of things but still does it. Forums say quite common on these. By contrast my Mondeo Mk4 estate doesn't suffer at all. Keep the AC on in auto which does the trick.


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## percymon (Jun 27, 2007)

Air Con is not just for cool air in the summer, its for supply of dry air in the winter to prevent misting.

RainX Anti-Fog product i used once a long time ago - if anything it made things worse in my non A/C car at the time.

If your A/C is blowing cold air on demand (on hot days) then at least its got gas and working as it should. If its getting noisy / gurgly or you hear a faint rumble at certain engine revs its probably low on gas.

Might be worth checking your pollen/cabin filter - to ensure its not wet and or blocked - don;t assume a dealer serviced car has had it changed despite the tick boxes in a service record !


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## bigkahunaburger (Jun 27, 2012)

This issue can often indicate residual moisture in a car, especially as it sound like you are keeping the glass really clean. I trust you don't smoke or vape in there? Perhaps a spilled drink has caused moisture build up? 100% check the cabin/pollen filter. Only a few quid to replace and easy to do. Are all the door seals performing? Is water (well, residual moisture) getting in anywhere? That could be the cause of the problem or at least make it worse. The reusable silica bags apparently help but don't expect them to cure it alone.

The anti-fog products are rubbish for the most part and would have a minimal effect in helping if the issue is down to something mentioned so far. 
That said, when you have resolved this issue, ODK Optics in a great glass cleaner and will leave you with an anti mist boost for a couple of weeks at time. It is so quick and easy to use that I leave mine in the car. the light from the sun when low in the sky suggests that all the streaks have gone from my glass. Even a great product like that isn't going to help if there is residual moisture build up in the car though.


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## MPS101 (May 6, 2011)

How old is the pollen filter as VAG cars from experience can fog up when the filter is past its best.


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## GeeWhizRS (Nov 1, 2019)

A few basics most will be aware of (maybe skip this post if you are), but for those that aren't, let's start here... the warmer air is, the more moisture it can hold. As the weather is now getting colder the warm, moist (breath etc) air inside your car will cool against the windows and want to condense to liberate that moisture, it has no choice. If the air isn't warm enough to sustain that moisture it will dump it on the first cold point it can. So you want to warm the windows, either by demister or heater. Depending on the design of the car, airflow from the heater will do a good job or a poor job. It sounds like a Passat hasn't got very good airflow across its windows. With the heater/air con moving air about as best it can over the windows, if it's still not having the desired effect, consider also cracking a window open to allow a throughput of air through the car to reduce some of the moist air.
Assuming there are no leaks as mentioned by BKHB above, and this is not a new problem for your car, it sounds like it's just going to be something to learn to live with.


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## Blanco92 (Oct 17, 2013)

Depending what year your Passat is, and assuming it's very similar to my A6... the reason these cars fog up is the pollen filter is nearly always damp to a certain degree. There is no cover over the top of the cabin filter. Instead, there's a wide plastic scuttle panel extension which is supposed to do the job of protecting the cabin filter (and battery & brake servo) from rain. Only in practice, it doesn't work so well.

We can talk til the cows come home about airflow and humidity but if the filter gets damp everytime it rains then that moisture is going to end up on the inside of your windows. It's a design flaw.

Mine's a 2003 A6 for reference.


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## lijongtao (Dec 1, 2017)

Is the pollen filter the one in the passenger footwell? If so I checked that today and it's fairly new bought in Feb. No drinks are allowed int he car and I have seat cover on all the time as my older children are doing paintin at college so I keep waterproof covers on constantly. Seals are good as far as I can see but will check again. As others have said, their Passats do this too. I have never experienced this with any other car i've owned. Thanks for the help guys, if someone can confirm the above question I'd be grateful. 

It is going in next week for a full service and MOT so will ask him to double-check the seals too.

Thanks

PS. 2014 Passat


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## BRUN (May 13, 2006)

it does happen a lot with a lot of VAG cars, my Fabia used to mist up quite badly, a fella at work has an Octavia and his does it too, along with most of the other VAG cars on the pitch at the dealers i work at


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## turboyamaha (Nov 18, 2010)

What sort of age are these Passats that are fogging up?


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## The happy goat (Jun 26, 2019)

I’ve had a VW golf and a seat Alteca both had the misting problem i found cracking the windows slightly helped first thing in the morning


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## Peirre (Jun 29, 2015)

With all the VAG cars I've had in recent years I stick a cheap dehumidifier tub in the boot. I get em from home bargains for around £1.70, they come with two bags of crystals (1+1 spare), they are the same as this one https://www.yorkshiretrading.com/pr...KQLVweSLN8zOT8rJyIiQZA6UXaEaNhtcaAkK5EALw_wcB


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## Demetrios72 (Jun 27, 2011)

MrPassat said:


> I had the same problem but I found the best solution is to turn the air-con on but dont use auto otherwise the fans go crazy. I like the temperature around 21C, a fan speed of 2 and the air being directed to my feet and the windscreen
> It seems that the auto mode directs the air to the dashboard vents with a high fan speed and that makes it feel cold.
> Not ideal I know.
> Maybe my technique is poor but I've always had problems with streaking when I tried anti-fogging products.


This is exactly what I do :thumb:

No issues whatsoever


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## BrummyPete (Jun 10, 2010)

turboyamaha said:


> What sort of age are these Passats that are fogging up?


I had a 16 plate and a 67 plate and both did it


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## MrPassat (Mar 30, 2018)

Mine's an 18 plate, been like it from new


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## lijongtao (Dec 1, 2017)

My wife has been out for the past 2 days and done as you've said. Air Con on and heat 69-71 and it is super now. Thank you so much for the help


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## LeeH (Jan 29, 2006)

If it’s stuck in recirculating mode you will have fogging issues. 


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## Andyblue (Jun 20, 2017)

lijongtao said:


> My wife has been out for the past 2 days and done as you've said. Air Con on and heat 69-71 and it is super now. Thank you so much for the help


That's good news :thumb:


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