I recently noticed when selecting 'demist' the aircon is automatically switched on, although it can be switched off. I can see some situations where aircon alone would act as a demister or normal heating alone, but can't see how both together work, at least in cold weather.

In cold weather, raising the temperature close to the windscreen will cause the moisture to evaporate into the air but cooling the air would do the reverse.

In hot humid conditions aircon would act as a dehumidifier. I can see that aircon plus recirculation would minimise windscreen misting by dehumidifying and maintaining that humidity but recirculation isn't automatically selected with demister aircon.

Is the aircon intended for comfort and only directed from the vents over the radio? If so it's still an unwelcome icy blast when I'm trying to warm up the interior as quickly as possible.

Do you prefer aircon automatically with demisting?

Actually...

I find that blowing cold air at a cold windscreen to demist it works better as the air is at a similar temperature.

And air-con dehumidifies anyway, which takes away the moisture on the screen.

The A/C removes the moisture from the air, and because there is no moisture this alone clears the screen far faster than heat alone. Try it out, from a misted up car point the vents at the screen and hit the A/C button and you will find it clears in seconds.

:iagree:

Air conditioning doesn't mean 'cold' - I have run it on pretty much all the time in all my cars fitted with it. My old car had climate control, so I just left it at 18 degrees all the time. Sometimes the air came out hot, sometimes it came out cold - but the car was always 18 degrees inside. As mannyo says, it dehumidifies the air, which helps with demisting.

Air conditioning doesn't mean 'cold' - I have run it on pretty much all the time in all my cars fitted with it. My old car had climate control, so I just left it at 18 degrees all the time. Sometimes the air came out hot, sometimes it came out cold - but the car was always 18 degrees inside. As mannyo says, it dehumidifies the air, which helps with demisting.

I think with 'climate control' you can select a temperature but car aircon is just cold until switched off.

The A/C removes the moisture from the air, and because there is no moisture this alone clears the screen far faster than heat alone. Try it out, from a misted up car point the vents at the screen and hit the A/C button and you will find it clears in seconds.

I would give it a try but then I'd be cooling the car interior when I'd prefer to be heating it up in this weather. I know the 'old' way when heaters weren't so good was to open all the windows, that did the same thing, just venting and cooling the car interior, but cold an draughty too.

I think with 'climate control' you can select a temperature but car aircon is just cold until switched off.

No - climate control has a temperature sensor and the ability to use it to maintain a set cabin temperature by altering the temperature of air it sends to the cabin. Air conditioning has all the same gubbins, but without the sensor.

Both my current cars have bog-standard air conditioning (not climate) and they will both provide hot air with the a/c turned on - it's just dry air, which is fab for demisting.

One of my cars is a MK2 Mondeo, which was the first one where they all had a/c - in that you can't turn the a/c off if you have the air set to only be on the windscreen for the very reason that it is best for demisting - and it comes out a temperature consistent with where the hot/cold dial is. And it has a quickclear screen - the only good feature on the car - thus making the whole thing unnecessary

Turn your a/c on, turn the temperature up, and it'll demist beautifully.

Interesting thread here:-

Air Con and Demisting: Motoring Discussion forum

Again... cold air to the screen will demist it even quicker due to the similarity in temperature!

Again... cold air to the screen will demist it even quicker due to the similarity in temperature!

Exactly.

If you can equalise the temp, then the mist will vanish!

Doesn't help the OPs reluctance to have cold air in the car though :-)