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Tsepz 12-02-2012 05:18 PM

Windscreen misting up on the outside
Hi Everyone, hope you're all having a great december.

So its summer down here in Johannesburg, South Africa, which means crazy hot days and stormy late afternoons and nights, so im doing a lot of driving at night (going out with friends etc...) and today i noticed that my windscreen is misting up on the outside, whether i have the demister (i think thats what you call it) on or off, when i have it on it clears it up on the inside and thats fine, but the outside steams up, and mainly in the bottom center and the middle, this makes for awful visibility when driving on a dark road even with brights.

So just wanted to know if this is normal? It began happening today, before it never happened, ive driven in some crazy storms pretty comfortably. Could it be the engine heating up? There are no warning lights at all, and the only problem my WJ reflects to me when i do the whole start trick is P1685 which is about skim key.

BTW, its a 2000 4.0 Limited, has been very well maintained by my Dad who passed it on to me when i got my drivers this year, he has never missed a service interval and it runs beautifully otherwise.


bill_de 12-02-2012 05:23 PM

Re: Windscreen misting up on the outside
My guess.

You have the defroster (demister) blowing cold air on the windshield. The warm moist air is condensing on the cold windshield. Same thing can happen driving through fog.

I just let the windshield wipers take care of it when it happens. It doesn't happen often.

Tsepz 12-02-2012 05:31 PM

Re: Windscreen misting up on the outside
That definetly could explain it, the whipers do take care of it but momentarily, will expirament more when driving tomorrow. I kept turning the defroster on and off, never thought of just maybe trying to make it blow warm air as even with the rain it is humid here.

I hope i am just over reacting, i love this car, and im scared of anything major going wrong, lol.

Thanks Bill, you've put my mind at ease. :)

Frango100 12-02-2012 05:43 PM

Re: Windscreen misting up on the outside
Same happens on mine. As soon as you switch the airflow to windshield position, the airconditioning will be switched on automatically (without the AC light on).
The cold air will indeed make the window quite cold as well and humid air will condensate on the windshield at the places where the air is blowing out.
Or you use the wipers to get rid of it, or you have to warm up the air blowing to the windshield.

Tsepz 12-03-2012 02:16 AM

Re: Windscreen misting up on the outside
Thanks Frango :)
Yep, will indeed try warm air, its going to rain all day today so i'll be able to try it.

Tsepz 12-15-2012 04:48 PM

Re: Windscreen misting up on the outside
Hi guys

So today it rained and then went a bit foggy, while driving my Jeep through the bit of fog (it was very little, none of it some points) my cars windshield got all misty on the outside, i tried warm air and it just got worse to a point where i couldnt see a thing, tried cold air and same thing, it wasnt raining at all but it was quite wet, cool and humid out as it had rained earlier, the only thing that helped was the windshield whipers, felt a bit retarded using them without rain but seems to be the best way to go at this point.
Its really frustrating, i just dont get why it does this, when i got home i even checked if it maybe the engine heating up, but it doesnt seem to be. I dont know, maybe its just time to sell the ol' girl and move to something new, she's around 12yrsld and has +310,000km on her, so im not suprised she is starting to show her age.

bill_de 12-15-2012 05:17 PM

Re: Windscreen misting up on the outside
Since fog is water vapor you can't help but get a wet windshield.

If you use RainX, the moisture will bead up and blow off the windshield once you hit about 35mph.

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