Windscreen Misting

[Legs]

A4 2.0 TDi 170 - During normal use I find it impossible to keep my windscreen clear without the a/c on. With the control settings on "auto" and when I am the only occupant the windscreen constantly mists up, it is even worse in the rain and worse again if there are more people in the car.

With its first service due I would like to know if it is only me experiencing this problem as I can ask the dealer to have a look at it during its service. Alternatively, if anyone has a suggestion as to how I could prevent this happening (assuming it isn't a fault) other than running around with the a/c permanently on I would love to hear it.

Many thanks

[streetfighter-r]

It doesn't matter what car you drive, if you have been using air-con, especially for demisting, then your windscreen will mist - this is also amplified with the damp weather.

Its simple to fix if you don't use air-con regulalry; turn air con off and go maximum heat on blowers until dried out. Easy!

[nevo]

The air con is there to de-humidify the air in your car and will stop misting, you either have a faulty servo on the demister flap or water entering the cabin,also check the recirc flap is operating.

[sleepingdog]

I don't think you are alone with this problem, I have new S4 and had 3.0tdi Quattro before - both have had similar issues and like you I am a bit stuck as to how to best resolve it. I put the temp up in the cabin and it seems to sort it out most of the time, also changing from auto to air blowing at windows seems to help. I actually thought it was probably my incompetence with the heating/ventilation rather than a fault, but definitely don't want to drive around with the AC on all day!

[legendamongus]

Try channeling the air directly onto the windscreen instead of leaving it on auto.


Why don't you want to keep the air con on? Is it just because of the effect on fuel economy or another reason? It IS the easiest solution to keeping the windows mist-free though.

[sleepingdog]

Try channeling the air directly onto the windscreen instead of leaving it on auto.


Why don't you want to keep the air con on? Is it just because of the effect on fuel economy or another reason? It IS the easiest solution to keeping the windows mist-free though.

Yip, not keen to keep AC on because of fuel economy, though to be honest I have never compared mpg with/without AC on.

[B8 TDI]

The Audi AC's are very economical, my own comparison has shown a difference of 0.01l/100km or +-0.3 mpg

[nevo]

They obviously use some power,but in the cooler months there're only running at low capacity,you should use it more often, just check there is air at the screen vents.

[sleepingdog]

The Audi AC's are very economical, my own comparison has shown a difference of 0.01l/100km or +-0.3 mpg

That's reassuring to know. Thanks.

[penrecon]

The Audi AC's are very economical, my own comparison has shown a difference of 0.01l/100km or +-0.3 mpg


I agree, my car shows a negligible difference of fuel consumtion whe using the A/C. Having said that I don't have any real problem with demisting without air con on, so I'd question if there's some problem with your car.

[A1287210]

Keep it ON always. Save money by buying your supermarket shop online and your insurance/energy on confused.com. If you are worried about the environment, think about this....the UK has 18 Coal fired power stations China....one country in the world is building 2 coal powered power stations a WEEK, if you want to save it by taking holidays in the UK as the amount of CO2 emitted per person flying to the US is equivalent to you driving your car for a year.....
You are now guilt free....and no more misting up windscreens....
Damo

[Legs]

Firstly, as the originator of this thread thank you for all your responses, I'm obviously not alone.

I live in Shetland - I don't need a/c very often! I prefer not to keep the a/c on all the time because of the effect on fuel economy and also I find that the interior of the car has a more comfortable atmosphere with it off, other than in high summer. Surely I should be able to drive around with the a/c off without the windscreen constantly misting up anyway?

I have tried channeling the air to the windscreen rather than keeping it on auto and that makes little difference. I also tried driving for while with the heater on full hot with the air directed to the windscreen as suggested in this thread. After 20 minutes I was almost passing out with the heat and it made no difference.

The clincher for me is this - my own car had its first service today and I was given a courtesy car by the dealer. 200 miles in the rain with 3 people on board, a/c off, heater set at 20 degrees and on auto - no misting what-so-ever. I'm due to collect my car tomorrow, asked them to check all was working OK, if it still mists up its going back until they fix it, I'm not paying £30k odd for a car and driving around with a misted windscreen.

Watch this space and I'll let you know how it goes.

[ScottyUK]

If you only use you're AC a couple of times a year then you run the risk of the rubbers drying out over time (appearently).

Make sure you run it regularly.

The last few days have been really wet but my cars been fine with AC off.

[Legs]

Just returned from the dealer as my car was in yesterday for its first service. Dealer didn't find a fault with the heating/ventilation but did carry out a "reset of the system".

I've only driven it about 2 miles but it looks better already set at auto, 20 degrees, a/c off; I'll see how it goes over the rest of the weekend, if its not right its going back.

[Legs]

Fixed.

I have now driven the car for a few hundred miles and its like a different beast, no misting of the windscreen at all with the heater controls set at 20 degrees, auto, a/c off.

I spoke to the service manager again, he advised that he had reset the heating and ventilation unit and replaced the pollen filter so it looks like there was something wrong there. Thanks for all your sugestions and help here, if any of you are suffering a similar problem try the reset and/or pollen filter.

[Geordie Amanda]

I always leave A/C on, but living in Manchester (it has rained an awful lot this last few weeks) I have found that the windscreen still mists up. It isn’t a full bodied ‘mist up’ such as days gone by when I didn’t have A/C, but it is still noticeable all the same. I find a quick blast with the front screen demist button, blows it away and then it usually stays clear for some time, before the process needs repeating, or the car is sufficiently warm and even in temperature and humidity, that it doesn’t mist again. Never had this problem before in my Imprezas, Golf, Toledo, Octavia or 1 series though :(

[Legs]

Geordie Amanda

Strongly suggest you take the car back to the dealer and get them to check the pollen filter and/or reset the heater control unit. Your symptoms sound pretty much the same as mine.

I waited till my car was a year old, it was the ONLY thing that niggled me about the car and I am SOOOOOOOOOOOOOOO annoyed I waited a year before getting it seen to. No misting at all now, not even at start up, just a clear windscreen all the way. Happy days!

[mrmarc]

Hi
Does any one know how to do this heating/ventilation system reset with vcds as i too suffer with misting of the windscreen.
regards

[Geordie Amanda]

Geordie Amanda

Strongly suggest you take the car back to the dealer and get them to check the pollen filter and/or reset the heater control unit. Your symptoms sound pretty much the same as mine.

I waited till my car was a year old, it was the ONLY thing that niggled me about the car and I am SOOOOOOOOOOOOOOO annoyed I waited a year before getting it seen to. No misting at all now, not even at start up, just a clear windscreen all the way. Happy days!
If I find time to go I will thanks. Got a very slight noise from the drivers door and the clutch pedal doen't feel very nice once the car is warmed up too (I have seem posts about this last problem)

[Zenerdiode]

Sorry I'm a bit late to get to this post, but hopefully I may help others.

Misting in the cabin:



Water ingress - Leaking seals or a favourite from the older Audis is blocked drains in the front plenum chamber. I was amazed in my old B5 Audi that the drains had blocked (one under the battery and the other under the brake servo) and there were litterally GALLONS of water sloshing around in there.
Switching OFF the AC - Normally the humidity in the air is condensed on the cold evaporator in the HVAC enclosure - and drains outside under the vehicle. Switching off the AC; the water condensed on the evaporator evaporates into the airflow and condenses on your now cool windows. Will eventually clear with fresh air drawn through cabin.
Re-circulation flap stuck shut - No fresh air is drawn in from the outside so the interior air gets heavily humid with expired breath and bodily sweat. This condenses on the windows.
Exhaust flaps stuck shut - these are located in the sides of the luggage compartment and vent the cabin air to expell behind the rear bumper on each side of the vehicle. Effect as 3. above.
Plugged cabin filter - Because it can't draw outside air through the filter it forces the air to re-circulate; hence same effect again as 3. above.


Hi
Does any one know how to do this heating/ventilation system reset with vcds as i too suffer with misting of the windscreen.
regards

[08] - HVAC
[04 - Basic Settings]
Select Group 001
[Go!]
[ON/OFF/NEXT]

Basic settings will now start. It moves each flap to their endpoints and calibrates their enpoints. Wait until the VCDS screen tells you that its done (older models show 0 0 0 0 in the measuring block windows, newer ones tell you that they're done) and then close out of Basic Settings. Re-check the error codes to see if any have been generated.

[A4 Lad]

Sorry for sounding so simple and hit me a slap to tell me to shut up but has anyone mentioned a pollen filter replace ?

[Legs]

I did!

Thanks anyway! Still loving being mist free.........

:beerchug: