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crank the climate control to like 28 or so... no fog. winnah.

I actually turn the temperature down to get rid of the fog.

Which works better to clear a foggy windscreen, aircon heating up or cooling down?

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I actually turn the temperature down to get rid of the fog.

Which works better to clear a foggy windscreen, aircon heating up or cooling down?

Cold air.

Think of a milk bottle when you take it out of the fridge. It forms condensation on the OUTSIDE, because the room temperature is much warmer than the cold milk.

Same thing. You get fog on the inside of the windows because it's much warmer inside the car than the cold air outside. Turn on the air conditioning as cold as you can get it to quickly normalise the outside and inside temperature of the glass to get rid of the fog.

Voila :D

both work.

But Cold air works x10 faster than warm air, especially if you have just started the car so the air will be warm at best if you use the heater.

in summary, use cold air :D

exactly !!!

so why is this even a topic of debate?

I've been using cold air to clear up the windscreen since the 80's. lol.

everyone knows it's the best way.

Yep, just what I was going to say. I spit in my dive mask, rub it all over inside of the lens, then rinse in seawater before putting it on.

Note: This may prove impractical for in car use. :D

spit?

I just set the fan to high speed, heater to high, and air source to fresh (not re-circulate). If you have re-cric set, you're just reusing the moisture laden air inside the car (from breath, having just come out of the gym or whatever), fresh brings in the moisture free (as it's cold) air from outside. This clears car within seconds.

Warm air can contain more moisture than cold air, so when the warm air inside the car hits the cold windscreen, it cools down, and can't contain all the moisture it has, so dumps it on the inside of the screen. Blowing hot (fresh) air over the inside warms up the windscreen, and as it's got a low relative humidity (moisture free cool air heated up, can then contain more moisture, so the RH goes down), it also takes up the moisture that is on the screen already. As a bonus, it's warm air so won't freeze your nuts off.

depends on whether the fog is on the inside or the outside. if it is on the outside then it is frost forming and you need hot air to get rid of it. you can spray your wipers but it comes back, except where the water actually hit the windscreen.

if it is on the inside then cold air for a short amount of time. if you leave it on too long you end up getting mist on the outside and have to go hot.

and fog-x is ok, but leaves a film which annoys me. i hate and haze on the windscreen. i don't know how some people drive with a dirty windscreen.

Edited by mad082

When I put my e-tag on the windshield it comes with an isopropyl alcohol wipe to clean the glass before you apply the holder.

I wiped the area around where I mounted it liberally, and it didn't really leave a film or anything on the glass (that I could see).

A few days later when it was pissing down raining, the area I cleaned was the only place where it didn't fog up.

I need to find some place that sells that stuff in bulk for cheap.

Fog-X didn't work for me (I found it fogs up worse) but I might have overapplied it.

charlier34 = from your name im guessin u have r34 or ur description says rb20det, wat car u got ???

i dont think on r32 u can have the air blowing on the windscreen without havin the ac on. but all i do is have the ac on and up the temperature to medium/warm. jus cauz u got the ac on duznt mean u cant set temp to warm so u dont freeeeeze.

u get isoprophyl alcohol from chemists :thumbsup: hope that helps

i didnt know until like 2 weeks ago that demister was onli on the back, lol

that was news to me then i realised my air con was on cold since i bought my car LOL i pay little attention to detail. cold air works a charm ;) just wear lots

of clothes if ur planning to go far

hey guys thx for the responses... i forgot and it is stupid of me for not stating that somehow my air-con doesn't work(maybe it needs a air-con regas, but let assume that air-con doesn't work at all ^_^) :/ haha i guess that explains how this debate popped up... and im pretty sure theres a few cars out there that has this problem to(i think) :thumbsup:

jvs007; i do have an r34... but i haven't edited my details hehe to lazy

A/C de-humidifys the air, thats the main point. If its cold, i chuck the climate control on about 24deg with A/C ON with the vents going to the windscreen, that works pretty quick. Cold A/C works a touch quicker.

  • 2 years later...

while warming up the car, hose the outside of the windows

set air con to OFF but allow it to flow the hot engine air through the feet vents and windscreen vent.

roll with windows slightly down(doesn't bother me as im a smoker)

rug up!

That's all i ever use the air con for.

I hate that No-Fog/Fog-X/Never Fog stuff, because it leaves an oily film on the windscreen that makes it look dirty and hazey in the sunlight... and if you wipe all of the oily stuff off, then you've just wiped off the product and it does sh1t-all!

I find just keeping the inside of the windscreen PERFECTLY clean and spotless is the best option. Then 10 seconds with a blast of hot air demists it quick as a flash! When your windscreen is dirty though, it takes AGES to demist the glass.

Absolutely agree with everything Merli said

Keep it very clean, and you are less likely to have the problem.

Also the RainEx AntiFog stuff is crap as mentioned, I put it on, then took it all off again, just became smeared everywhere.

It is also about keeping the inside of the car dry where possible. So leave umbrellas etc in the boot and anything else that is wet. I occasionally put a tub of those moisture absorbing things in the car overnight over a few days. It sucks up all the moisture in the air and converts it to water in a tub. You can buy it from the supermarket. It helps, especially when the air is very humid in the car, and moisture is attached to your carpet, seats etc.

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