Rear window condensation

scotty76

scotty76

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Now the mornings have turned a bit nippy I find an old problem has returned. Thick condensation on the rear window. As in unusually thick, 10 minutes plus of the screen heater on and it's still not clear.

I've checked the carpets and interior of the car and they are all fine. No evidence of water leaks. After 3 years of owning the car I'm beginning to think it's just a "feature" as it has always done this. Does anyone else get this?
 
Hi..

Yes I have noticed this as well on the back window,

I usually stick the rear heater on and it clears as the car warms up..

Cheers

Matt
 
Give the inner glass a clean with a decent glass cleaner. If it's not be cleaned in a while it's probably just dirty. Dirty glass is more prone to condensation.
 
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My wife's Golf was bad with condensation, just changed the cabin pollen filter and it seems to have cured it. The old filter didn't even look that bad but I'm guessing that if fresh air can't get in freely it's a bit like keeping the recirculate button on? Might be worth a look.
 
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Thanks for the suggestions. I've been out at lunchtime and cleaned the window. The pollen filter was changed over the summer so hopefully that covers that angle. I will wait and see what tomorrow brings.
 
dpaz said:
Dirty glass is more prone to condensation.
Click to expand...

How does that work??
Normally, condensation forms from moisture on the coldest surface it can find. In a car's interior, this would be the glass. In the OP's case, there's definitely moisture contained within his car for this to be happening.
That's not to say there's any kind of leak however; I get the odd spot through the colder months but it's more than likely to be that I'm in and out of the car with wet shoes and not doing many miles, so the moisture's not fully extracted via the aircon.
 
Open all the windows and let the heat out of the car when you park it up at night.

Don't forget to close them obviously.
 
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Pat. said:
How does that work??
Normally, condensation forms from moisture on the coldest surface it can find. In a car's interior, this would be the glass. In the OP's case, there's definitely moisture contained within his car for this to be happening.
That's not to say there's any kind of leak however; I get the odd spot through the colder months but it's more than likely to be that I'm in and out of the car with wet shoes and not doing many miles, so the moisture's not fully extracted via the aircon.
Click to expand...

My theory is the dirt provides more surface area for the water droplets to form on.

But rather than speculating, why don't you test the solution for yourself? I know for a fact it has worked for me on several of my past and current vehicles.

Other points to consider

1) Why do new car's not fog up as easily as old?
2) Why do finger and hand prints fog up first and are more noticable?
 
No speculation here bud, my windows are pretty much spotless on the inside :)

I'd say with new cars it'd be down to the fact that everything's, well, new! All the weather seals are new and unperished rubber, pollen filter will be clean, windscreen won't have been changed, sunroof drainage tubes won't be clogged up, etc etc
 
audi upgrades
Wow, who thought condensation was this much fun?! :)

Seriously though. I had issues on a previous car where someone suggested cleaning the windows thoroughly and this did help, whatever the science may or may not be. I enjoy detailing my car but interior glass cleaning is something I don't often remember to do.

I've also had water leaks on other cars which have resulted in serious condensation, so I know what the looks like too. On my B7 it's just the rear window, nothing really to report on the other windows.

@sidibear hadn't considered that angle, I'll give that a go next if there's no progress.
 
Is your car parked with the rear window facing east, where the sun comes up?
 
No sunshine when I leave for work, it's usually dark. I'd say the rear window faces North.
 
took the topic right out of my mouth - however thought i'd look silly raising such a question - but yeah found this issue on my b7 aswell..

windscreen takes 2 -3 attempts before it starts to clear (when it turns off have to turn it back on)

will try the cleaning theory - let me know how you get on

cheers mate
 
No such thing as a daft question. It all helps. That's what forums are for.
 
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My rear screen did this today, fronts fine tbh once heats on it, tomorrow I will be doing some serious internal/external glass cleaning now my cracked front has been replaced & also coating outside with some gtechniq G1, I'll be checking for wet floor aswell as I suspect somethings wet inside due to the slight smell.
 
Last edited:
Yes sorry, corrected now, long day lol.

On another note, your plug stuff is on order for tomorrow, with few things arriving end of week afaik, update directly asap :)
 
scotty76 said:
Now the mornings have turned a bit nippy I find an old problem has returned. Thick condensation on the rear window. As in unusually thick, 10 minutes plus of the screen heater on and it's still not clear.

I've checked the carpets and interior of the car and they are all fine. No evidence of water leaks. After 3 years of owning the car I'm beginning to think it's just a "feature" as it has always done this. Does anyone else get this?
Click to expand...

Im glad im not the only one. I did the exact same thing. Had the rear window misted up and still is currently as we speak. I have cleaned all interior glass. And still get the issue.

I checked carpets, ,mats and no damp any were and pollen filter was recent. I have even gone as far as closing the front vents to see if its maybe external air mixing with internal air. But nope made no difference.

Considering I do detailing part time. I have noticed cleaning customers cars windows especially the inside rear one, after 4pm is a NO GO! Just breathing inside the vehicle sets the back windscreen off and its such a pain. Especially since the weather has taking a turn. It has become a lot more noticeable.

Having said all this I was in London this past weekend and I thought when I am out in the evenings I am going to look at other cars rear windows and true as anything there was E46 bmw, Mercs, Vaux you name it they all had misted inside rear glass. The one that caught my attention the most was a 12 Plate Jag XF was foggy as anything. BUt okay in fairness it could be there was moisture or someone got in the vehicle and they were damp. Just was a shock to see something "recent" build to have the same issue. So i felt pleased about that.

Going back to the point Scotty when I first noticed it a lot of people I spoke to said do the following check your boot material for any damp patches or spots especially on the left side were there is the little storage unit is. The other suggestion was to check were the spare wheel is and see if any water is there. Then lastly which seems to be the more common thing is that, it has something to do with the air gets into the cabin from were the High Level Brake Light is in the centre of the window. If you open the boot and turn ur head upwards have a look if you can feel the change of temp between the boot and the cabin. Whether its true or not I am not sure as I have not had the opportunity to check.

I am keen to see if someone finds a solution.
 
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borrow a dehumidifier works on my old landrover that had water running of the inside of the roof!
Maybe worth runningvwith a/c on all the time?

Lynall
 
Giosabcsl said:
Im glad im not the only one. I did the exact same thing. Had the rear window misted up and still is currently as we speak. I have cleaned all interior glass. And still get the issue.
Click to expand...

Wow Gio, that's quite a write up! I was curious as to why it happens but you sound genuinely annoyed! :)

I expect the rear window to mist up, it's just that time of year. What's different is on our other car about 1-2 minutes of the rear screen heater on is enough to de-mist it. On the A4 I reckon I reckon it would need to be on for 15 minutes to do the job completely.

I think I've answered my main question which was does anyone else have the issue and it sounds like the answer is "yes". :)

If I could be bothered I'd try this CarPro - Fog Fight - Clean Your Car but I hate cleaning interior glass.
 
audi upgrades
To bring back this thread Scotty76,

I managed to resolve my issue on the interior misty windows.

After a lot of thought, I decided that no matter what car these are Audi's and are German built quality machines. So I thought well surely the car did not have this issue when it came from the factory so nor should it have it now.

And man what a relief not seeing my rear window or my rear side windows not misted up after spending hours outside working on her during the course of the evening not a single drop of water or moisture in the car.

Then to go out for a celebration drive. To hear my drivers window go clunk, bang, grind in that order..... My window cable snapped...which is another story on its own at least my window motor did not strip or get damaged as that is one costly part.

From one issue resolved to have another arise. And what was I saying about German build quality lol :faint:
 
Unfortunately its a trait, don't use ebay cheaper units either, as they're known to be crap & break soon, unless its original oem part.
 
NHN said:
Unfortunately its a trait, don't use ebay cheaper units either, as they're known to be crap & break soon, unless its original oem part.
Click to expand...

Oh don't worry on my B6 1.8T I had the exact same issue. And tried to be a hero and bought the repair kit off ebay. Well that last all of one day then bought the full kit off ebay again bit me in the ****. And went OEM and 4 years on the owner still hasnt complained about the window. So results I hope to do the same with my current one.
 
Sorry about that I should have said. Got distracted...

Basically I removed the battery and the pollen filter box. And the famous chambers under the battery were blocked.

So I figured how does that affect all the way at the rear of the vehicle...who knows but also had 2 or 3 rips in my pollen filter.

During the evening while cleaning that entire chamber under the battery usually by now the car would be misted up as described in the above posts. It was completely clear not a single ounce of steam or mist in the car. Which seemed like a result.

I cant exactly put my finger on the fault that was causing the issue but I did realise that half the pollen filter actually sticks out the back of the pollen filter box which seemed strange as I didnt notice this before but it is the nature of the design to suck air in kinda like a intake breather. So I thought some form of moisture must be getting through.

Now I did notice quite a bit of water next to the pollen filter and there is padding there that seems to absorb moisture. I dried that up.

And as I say its been dry for 2 days now. Thou it seems its creeping slowly back in only to the rear window which is slightly misted now but I can only put that down to the fact because I have no rubber seal on the door to repair the broken window mechanism.

Hopefully you can make sense of it.
 
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Windows still steamed up badly this morning. I cleaned them well so that didn't work. Guess I need to check the drain holes. :)
 
scotty76 said:
Windows still steamed up badly this morning. I cleaned them well so that didn't work. Guess I need to check the drain holes. :)
Click to expand...

Give me a shout if you in the bracknell area can offer a hand if needed.
 
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Is it simplistic to say "Check your drains"?
The scuttle area, where the air is sucked into the car, needs to be clear of standing water, so as you drive, the splashing puddles cannot get sucked into the air inlet.

And obviously the seals and draining areas around the doors and boot need to be clear and clean.
And sunshine roof is another!
 
Nothing seems to be blocked. No standing water. A bit of junk in there, will have a go at clearing it out when I get a minute.
 
Oh, forgot to say. I've got some CarPro Fog Fight coming so will see if that helps first. More out of curiosity to see how good it is.
 
scotty76 said:
Oh, forgot to say. I've got some CarPro Fog Fight coming so will see if that helps first. More out of curiosity to see how good it is.
Click to expand...

Is it ok to use a product on the rear window? (Heated element) As much as I've wanted to I've never used anything on the rear screen other than water. I'm sure I've read somewhere that you shouldnt??
 
Hi mate, i know you mentioned that the cabin pollen filter was changed recently but the one i changed looked fine as well. Maybe you could take it out and leave the car for a day or 2 without a filter just to see what happens?
 
So putting my money where my mouth is, I got some Fog Fight and am quite impressed with it. I applied to the back windscreen and the front, side windows. It definitely helps. I would say that its reputation for streaking is true. In the daylight it looks fine but at night with car headlights following I can see some streaks on the rear screen. Not many so may just need to be more careful with the final wipeover next time. Oh and it was 4C when I applied it which is not ideal. CarPro recommend applying it after you've been out for a drive and the car is warm to help. I didn't do this.

So overall, one to try but I don't think I'd put it on the front screen in case of streaking.

I'll keep you posted as to how it goes over the next few weeks.
 
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As promised, quick update. Had the Fog Fight on a week now. I've had no issues with rear window condensation. This week we've had a mix of frosty mornings or wet mornings so a bit of everything. It's working well. Will update again (when I remember). :)
 
So quick update. Car has been sitting on the drive for 2 weeks and condensation is back. That's OK. Will clean the glass and re-apply. Happy with the performance.

In other news have noticed Fog Fight smells like Shandy Bass. WTF? :)
 
Only had my 05 3.0 tdi quatrro estate for about three months & like everyone else my rear screen is saturated, condensation comes from moisture so i had a look where the spare wheel lives, quit a pond of water, yellowy in colour like lager, no signes of wetness anywhere higher than the well, dried it all out, no condensation this morning.
 
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A thought crossed my mind this morning, went to move the oh's car which was condensated up across the screen, hand in door pocket for the duster to wipe the screen & it was already wet, a prime source of condensation !!!, how many of us do that in the morning, wipe the screen & bung the cloth back in the door pocket in our haste to get going then forget about it.
 
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