Windscreen Steaming Up Outside

[Disca]

God I am whittling through bits daily just trying to get an understanding of what issues I may or may not face with the car! Apologies!

So I have noticed the windscreen often steams up if I have the aircon blowing on it, the condensation appears on the outside of the glass though, so disappears when you hit the wipers. It is noticeably less bad if I direct the blowers down onto face / feet.

This morning it did however take an absolute age for the windscreen to stop steaming up in general.
What do the diagnostic powers that be think this one is ?

 

[DavidM]

Try washing your windscreen with a mix of vinegar and water which may help.

 

[TaffZee]

Air moisture content outside

 

[Disca]

Try washing your windscreen with a mix of vinegar and water which may help.

What's the science behind this?

 

[littlefeller]

will watch this thread, i have the same issue, my previous car was the same.

 

[Disca]

will watch this thread, i have the same issue, my previous car was the same.

Glad I'm not the only one!

 

[Cooper]

I am no expert but I suggest that the cold air blowing onto the window is making the [warmer and more humid] air on the outside condensate due to the huge variation in temperature. To remedy do not allow the aircon vents to blow on the windscreen or make the temperature higher [warmer]. Just allow the aircon to blow out the feet or face section.

 

[Disca]

@Cooper that is what I am currently doing. However even with the directional switch fully pointed down (between feet and floor) I get a small amount of buildup still, seems that the vents still have a small amount of air coming from them even when it's re-pointed elsewhere. It's no where near as bad when not aimed at the windscreen but still causes a couple of little circular condensation patches on the passenger side of the car primarily, that line up with openings of the air vents.

 

[Cooper]

Yup, its just too cold in that area I think.

 

[Disca]

Hmmm, I'll try throwing some of my anti-mist glass cleaner on it tomorrow, otherwise the water and vinegar option shall be next.
Was wondering if was an issue with the AC or anything like that, hopefully it's just the abnormal warm / muggy weather at present.

 

[EnthuZiaZT]

It sounds a bit strange, but have you changed your cabin filter recently. It may be the old one has become clogged or damp or both and might be the cause of your problem.

Mike

 

[Disca]

@EnthuZiaZT I don't actually know, I shall add that to the list of small replaceable bits to obtain soon

Edit: Google seems to suggest none of the Z3 range had a cabin air filter, can someone confirm?

 

[littlefeller]

i think it has more to do with the angle of the screen, on cars with a more vertical sceen it doesnt seem to be an issue, but the zed and worse my previous car had very slopped screens, i dont run the blower but it wont stop misting for around 10 min driving, any other car i use doesnt do this, unless it is something im cleaning my cars with

 

[Disca]

My previous two Z4s never had an issue with it and I think they have a fairly slopey windscreen? What do you clean the cars with so we can avoid it

 

[DavidM]

What's the science behind this?

I believe the vinegar in the mix removes any chemicals that may be on the windscreen that attracts moisture. Worth a try?

 

[Disca]

I believe the vinegar in the mix removes any chemicals that may be on the windscreen that attracts moisture. Worth a try?

Sure is! Got oodles of the stuff from trying to de-limescale the kitchen taps, damn you London water, so shall re-purpose it!

 

[Redline]

Humidity was at 98% at 7am this morning. Could tell because of the fog. Water will very quickly condense out onto something colder which is exactly what the Aircon will be doing to the windscreen until the engine warms and the heater starts heating up. Cleaning the windscreen may help reduce places that seeds the condensation but if it's an old screen there will be lots of micro scratches that will support condensation formation.
On the inside your Aircon will already have condensed any moisture out so will be dry by the time it's pushed out the vent.

 

[5harp3y]

cold windscreen inside
warm air outside

=

condensation

 

[Cooper]

The best thing to clean windscreens [and many other things] is isopropyl alcohol. Put it on a clean rag and clean [do not spray it]. Seriously it cleaned up my windscreen in seconds after I tried many other products without success. It also stopped the inside from fogging up so easily.

 

[TaffZee]

What happens when you walk from a cold environment into a warm steamy bathroom wearing glasses? Same as your car, when the windows are cooled down any moisture in the outside air will condense on the surface. Regardless of what you put on your screen.