Alright!

If I've had the aircon on and then switch it off all the windows mist up. Had my GP for a year now, and it's always done this. I've never had a car with aircon before and was just wondering if this is normal?

It's called condensation, the inside of the car is cooler than the outside of the car so all the moisture in the car is drawn towards the warm windows (outside).

Nice. What about when it's colder outside and it still happens? And what about when it still happens although the heaters are roaring out hot air from the depths of hell itself?

Like I say, this happens when the aircon has been on (at any temperature) and is then switched off.

It will happen. Is this your first car?

what setting you got it on? blowing on your windscreen?

go to a motorbike shop and buy some anti mist spray for crash helmet visors. spray on, wipe off, never need your fan again. well other than winter......

blair said:

Alright!

If I've had the aircon on and then switch it off all the windows mist up. Had my GP for a year now, and it's always done this. I've never had a car with aircon before and was just wondering if this is normal?

Click to expand...

This can happen if you leave the recirculating button switched on for any length of time. It might also have the word MAX on it to indicate best air-con temperature.

Yes, it does give you max air-con but at the expense of getting rid of the stale, moist air in the car.

Use it sparingly and it should not be a problem. Certainly should not mist up the windows if the recirculating button (Max) is off.

Just in case you have a problem with this button, the fan is quite a bit higher with it ON. Switch it off and the fan (blower) will drop a very noticable amount.

A small amount is normal. I find when Ive had mine on, then use the car shortly after a little bit builds up on the screen then clears.

Water builds up in the condensor. It's worse in humid weather, such as now, due to the higher amount of water vapour in the air - ie humidity. It's perfectly normal. I wouldn't bother putting any anti-mist spray on your windows, prob a waste of time. When it builds up, just use the aircon for a minute or two to clear it again. It's happened in every car I have evr had with aircon, it's just a "feature" of the system.

Cheers guys, at least I know that it's normal. Being a techy teacher means I'm predisposed to wanting to fix things!

And no it's not my first car, I used to have a Clio until somebody pinched my exhaust mid section and cat converter!

I have just posted about the same problem - this is not condensation.... I had the same a year ago and the Fiat dealer said the aircon drain was kinked so it wasa sitting full of water. They fixed it for free (suggesting it is easy) but the problem is back. I'm trying to find out how to access it.

Air absorbs moisture like a sponge. The warmer the air, the more moisture it can hold, hence some hot days being very humid, and cold days feeling dry.

Think of when you take something out of the fridge and stand it on the kitchen work surface. It gets wet on the outside. This is because the air touching it is cooled, so cannot hold as much moisture, so it deposits it onto the cold surface. Same thing happens when the air hits the cold windows inside your car, (or your house if you don't put the heating on).

As the air enters the car through the aircon unit, it is cooled. A lot of moisture is deposited in the cooling unit, so the air entering the car is drier. As the droplets in the cooling unit increase, they join together and when big enough, drain out the bottom. On hot days, aircon cars will often leave puddles of clean water.

When you turn the aircon off, the cooling unit quickly warms to ambient temperature. The air entering the car will collect any moisture that has not drained out, so increasing the moisture content entering the car, hence the rapid misting up of windows.

If the aircon is used on damp days, it needs to be left on to maintain the drier atmosphere inside.

Because the air entering the car is drier, the driver especially should ensure they have plenty to drink, as they will lose water more rapidly and may dehydrate on longer journeys. Wearing some contact lenses can also be a problem if the drier air dries the eyes and the lenses start to shrink. Wear glasses.