Fastest method of demisting

The message from "Mark Hewitt" contains these words:

Dry the inside of the car out better. Make sure you have the air set to recycle, and don't jump into a cold car fresh from the shower when you're still steaming.

My Monty's steaming up a bit at the moment, but that's 'cos it's got a soggy carpet somewhere.

THis is often a problem with a new car - the windscreen gets very dirty on the inside - I think it comes from the plastics. I find that with a new car I have to thoroughly clean the windscreen every couple of months to stop it misting.

why would it take anything more than a few seconds to demist fully with the ac on?

4 of us regularly jump into my mates Saab 95 and it steams up in seconds but as soon as the AC kicks in it's cleared up keeping the interior glass clean is one thing, but if it's not demisting in a matter of seconds then maybe the AC isn't working as it should and don't leave it on recycle as it just traps the moisture in the air inside the car and it takes longer to demist

95% of the time that is exactly what happens. However this morning I had to sit for about 5 minutes waiting for it to clear.. As far as I can tell the A/C is working, but I will double check..

You should have gone for the heated windscreen option?

It needs to be on recycle to start with. If it is on recycle, the AC will be taking all the moisture out of the air. On a damp morning, letting fresh air in will be letting more moisture in. Opening the windows may have the same effect if it lets air in.

You will need to turn off recycle once you are cleared. I usually wait till the heater warms the glass, then turn off the AC and recycle.

Bob

Yes!! :-(

I'm off to start a new thread ;-)

Does it have a pollen filter? My Astra always misted up really badly the day *after* it rained. Vauxhall dealer suggested the pollen filter was clogged, so I chucked it out. Problem solved, so I bought a new filter.

Bob

My car has a 4degree cut off for the AC, if the engine bay temp is

Was it really cold outside? The A/C usually doesn't run when the temperature is below 4 degrees C.

Hmm was mighty chilly this morning so that might have been the case! Once the screen began to demist it did so with its usual rapidity however I had to wait a while for it to start, perhaps this A/C cutout was the problem, and I had to wait for the engine to heat up before it would start.. I guess lightly revving the engine to produce some heat may speed up this process? At the cost of petrol of course.

Which is exactly what happens when you press the 'demist' button on many japanese cars from the mid-90s onwards.

You get recirculated air, aircon, full heat (not that it matters as the engine's cold), full fans directed at the windscreen for about one or two minutes. Then it switches to outside air and slows the fan a bit after that to keep it clear. Once the engine's up to temperature you can switch back to normal climate control operation to warm your toes :)

You need to remove the moisture from the air inside the car using the aircon until the air and glass temperature is sufficiently high to hold the moisture without it condensing on the glass. Then you can switch to outside air, as any moisture coming in with it won't end up on the windscreen.

Rich.

Right then. The consensus seems to be... Fan set to 4 (maximum) Fan set to windscreen only Heat set to maximum A/C ON Recirculation ON Windows closed.

Then wait! Can turn down the fan and heat once the demisting is complete.

The delay at present going from other posts seems to be that the engine is too cold and the A/C won't start. Would gently revving the engine while still stationary speed up the heating and hence make the A/C engage faster?

Agree with all this, but what about us poor folk who still don't have A/C? What should we do, since just putting recirculate on won't dry out the air like A/C?

Al

if its really bad get an old towel place at the bottom of the screen and use an old wiper blade inside - i usually wiper blade all my windows before i set off anywhere if the things are steamed up - mirrors as well. my bmw e30 seems to demist really well - not like the old vw beetles i had (now they were a problem - ice inside the windscreen......)

A bit ungainly, a wiper blade... There are smaller things available, like a

4" wide T shaped thingy with an ice scraper, squegee and sponge all in one for about a quid.

Bob

Clean the windscreen properly. Autoglym glass cleaner is good, as is neat screenwash. The difference between a mucky and clean screen is incredible. Fogs a lot less.

You'll be able to tell if the A/C compressor is engaging - from outside the car, you'd likely hear quite a noticeable click. From inside, you'll likely be able to feel a slight loading on the engine, and a blip in the revs.

One thing that has occurred to me, that I've witnessed in numerous cars - if you have the air-con on a lot, moisture can build up on the evaporator - especially if the air-con is running up to the point you turn off the car, previously. So when you start, again, quite often this moisture is then blown into the interior and mists up the windows for a brief period.

It's good practice to run your fans for a few minutes at the end of each journey (say the last 5 minutes) with the air-con off, giving the evaporator a chance to dry out - and hopefully, stop the build up of gungy, smelly stuff on it, too.

The message from "Bob Smith \(UK\)" contains these words:

On a Montego!

Commonest cause of cars being misted up is driver setting the air control to recycle. You see Corsas steamed up to the eyebrows on fine days 'cos of this.