I've had this problem a couple of times recently, I've been driving along, all the windows clear, and then I put the air con on with recirculate, and then the windows all begin to fog up! I have no idea what's causing this problem, and it's not something I've read about on here before! I've done a search but can't find anything relevant!

A bit of background info: -

I've recently sealed all the doors as they were leaking, and have had problems with leaking/fogging for the last year.

I changed the pollen filter at the weekend to try and help the problem.

I can't think of anything else relevant at the minute. I find the windows clear better in my car when I don't use the aircon and recirculate, so there's definitely a problem with the air conditioning system somewhere!

Help please!!

The aircon won't come on below 5 degrees. Does it still mist up with recirculate and aircon off?

As he said ^

Make sure your carpets are dry by putting newspaper down under the mats as well!

The aircon won't come on below 5 degrees. Does it still mist up with recirculate and aircon off?

Doesn't mist up at all when it's off. When I turn it on then it mists up, even if it is below 5 degrees. It can mist up in a couple of seconds and the whole front screen can become completely fogged, which is very dangerous!

As he said ^

Make sure your carpets are dry by putting newspaper down under the mats as well!

The reason I wanted to have the air con on is so that I can dry out the carpets more thoroughly, but I can't even use it at the minute. Is there any technical reason why this problem is occuring?

Edited 29 November, 201015 yr by Bezzy

Seriously, don't use recirc. Otherwise, all you're doing is blowing all the damp air you've just exhaled into your cold screen. Fresh air wherever possible is the way forward...

My old car did this I couldn't even put the the fans to just the windscreen it would all fog up I couldn't see a thing I'd have to open all the windows but it only happened in the rain. Can't you buy special spray to stop it fogging? I used to buy still for my motorbike helmet screen

If it does it with fresh air too - maybe a new pollen filter is needed?

Seriously, don't use recirc. Otherwise, all you're doing is blowing all the damp air you've just exhaled into your cold screen. Fresh air wherever possible is the way forward...

Ok, so to clear the screen on a cold morning, I should just use air onto the windscreen, without air-con (which probably wont be working as it's below 5 degrees), and without recirculate?

I have said it many times - the AC system in this car holds on to moisure somewhere inside, then chucks it out when you turn the AC on.

My car went in twice and the dealers told me it was normal, as all the other cars on the forecourt did the same thing. I have never had a puddle of condensate under my Fabia from the AC. Ever.

Now I only use AC with recirc to minimise the amount of water condensed from the fresh air, and leave the car with the vents set to footwells only so that any moisture blows away from the screen. And in winter i warm the glass up with luke warm water to de-ice, preventing steaming up in the first place.

Works for me.

I have said it many times - the AC system in this car holds on to moisure somewhere inside, then chucks it out when you turn the AC on.

My car went in twice and the dealers told me it was normal, as all the other cars on the forecourt did the same thing. I have never had a puddle of condensate under my Fabia from the AC. Ever.

Now I only use AC with recirc to minimise the amount of water condensed from the fresh air, and leave the car with the vents set to footwells only so that any moisture blows away from the screen. And in winter i warm the glass up with luke warm water to de-ice, preventing steaming up in the first place.

Works for me.

Thanks for that, that was something along the lines of what I was looking for.

Do you think that the moisture which the system retains can be removed by using the air con on recirculate? On my old car air con and recirculate on full blast was the way to remove any fogging - used to take seconds to clear. I'm thinking that with the water ingress troubles which the Fabia has creates this knock on effect of fogging with the air con? I may try driving with air con on and recirculate with fans on footwells to see if I can clear the system or something.

Try a dehumidifier in the car for a few days?

What's your obsession with recirc? It isn't warm enough for the A/C to work, so all you're doing is drawing damp air into the dash, where the moisture will condense (in all the wrong places) and cause problems in the future. Much better to keep it on 'fresh air' and then the moist air will be pushed out the back of the car as you drive along...

What's your obsession with recirc? It isn't warm enough for the A/C to work, so all you're doing is drawing damp air into the dash, where the moisture will condense (in all the wrong places) and cause problems in the future. Much better to keep it on 'fresh air' and then the moist air will be pushed out the back of the car as you drive along...

+1 on that

What's your obsession with recirc? It isn't warm enough for the A/C to work, so all you're doing is drawing damp air into the dash, where the moisture will condense (in all the wrong places) and cause problems in the future. Much better to keep it on 'fresh air' and then the moist air will be pushed out the back of the car as you drive along...

My obsession is that on previous cars it was the best way to clear a fogged up windscreen and I don't fully understand why the Fabia should be so different. As far as your advice goes, yes, I'm already using fresh air, as I previously said, because my AC fogs up the windows. I actually do not understand the AC on the Fabia, and you're not very clear with your explanation. If the AC doesn't work, then why does 'turning it on' change what air is drawn into the cabin? If the air it begins to draw in is different to other air, then clearly it is 'working' as such, as it has changed the air being drawn in. What I want to know, as per my original question, why is this air damp, and is there any way to clear it?

So far the only person who has explained the problem to any extent is micklecats. I wanted to check that the air conditioning system is operating as 'normal', because from my experience it doesn't operate the way it should! I've never known another car that fogs up all the windows when you turn the air con on.

Crocket - thanks for your constructive comments, I do not have a dehumidifier which is accessible to me, or anywhere I could use it (I presume they all run on electric?) due to my current living arrangements. This will change soon and maybe I can use one then.

What's your obsession with recirc? It isn't warm enough for the A/C to work, so all you're doing is drawing damp air into the dash, where the moisture will condense (in all the wrong places) and cause problems in the future. Much better to keep it on 'fresh air' and then the moist air will be pushed out the back of the car as you drive along...

Make that +2. Turn recirc off. The nly thing it's good for is if there's a car in front chucking fumes out.

The A/C is deactivated below 4 degC (when the snowflake appears) to stop the evaporator freezing up. Effectively, when it's cold, the switch on the dash does nothing!

As for the air being damp, there are many reasons for this: you're breathing out moisture; you've come from a warm house where the humidity is much higher than the cold air in your car, and so your clothes have moisture in them; possibly even the carpets are still wet from when the doors were leaking (as I mentioned earlier!)

Now, without the A/C evaporator functioning, there's no means of dehumidifying the air in the car and it will just condense on any wet surface, as you have been finding.

And for what it's worth, I always see a small trickle of condensate under my car in the hot weather from the A/C, so possibly mickelcat's car had a fault which yours also has? A blocked drain, perhaps?

With the AC on I use recirc as it does not draw in any more air from outside, which is not dehumidified by the AC system (therefore containing more moisture).

Yes it keeps all the same air inside, but it does not add any moist air from outside - lets face it if the AC is on to keep the windows clear its usually wet or humid outside??? The wetter it is the more moisture will be in the air (humidity increases) and drawing air in will only make it worse.

Once the air inside the car is dried by the AC it will collect no more condensate becasue no more fresh humid air is coming in.

When the AC is off I never use recirc as, like you say, it keeps the moist air inside and makes things worse.

The two situations are different.

If the OP tries what I suggest it should improve - it has for me and I have been having this since I first got the car.

It took me a while to get my head around it, but it definitely works.

Bezzy - please let me know how you get on matey

HTH

Sorry, but the air from outside IS dehumidified by the A/C - why wouldn't it be? On both 'fresh air' and recirc, the air passes over the evaporator, and this (when it's not deactivated by the cold) is what both cools the air and dehumidifies it.

And as for 'no more moist air coming in', you're ignoring the fact that you are giving off moisture yourself. Have you never breathed on a cold window? You breathe out at least 20ml of moisture per hour, and without the dehumidifying effect of the A/C, or the action of the 'fresh air' setting to maintain air-change rate, this will mean the air in your car becomes saturated at 18 degC in under an hour - more like 5 minutes at 0 degC (i.e. in contact with your cold windscreen).

The thing you have to remember is that the relative humidity of the air you breathe out is virtually always higher than of the atmosphere - definitely on a cold day - and if it isn't, you know about it (if you've ever been to the Tropics, you'll know what I mean...)

At the end of the say, high atmospheric humidity is a warm-weather problem - I can't put it any more succinctly than this:

The hotter the air, the more moisture it can hold., from http://www.bbc.co.uk/weather/features/understanding/humidity.shtml

So, you're basically saying I shouldn't be using air conditioning or recirculate to clear the fogging? What settings do you suggest for fan speed, heat, and then a/c and rc to clear fogging in the quickest time?

Well, the A/C won't be on below 4 degC, as described above. When it's this cold, the air outside is realtively dry, as well and it's the driver (and/or any passengers) that will be the source of any moisture that fogs up the windscreen. You can check this by starting the car and putting the ventilation to '4', 'fresh air' and 'screen' BUT NOT GETTING IN THE CAR STRAIGHTAWAY. Maybe use the time to scrape off any frost or snow, but don't leave the car unattended (obviously). Temperature setting is irrelevant as the car won't warm up for quite some time in this weather, but like this, the screen should not mist up. Once the car's been running for a minute and the air's moving nicely, you can get in and be on your way fog-free. IME, anyway...

Well, the A/C won't be on below 4 degC, as described above. When it's this cold, the air outside is realtively dry, as well and it's the driver (and/or any passengers) that will be the source of any moisture that fogs up the windscreen. You can check this by starting the car and putting the ventilation to '4', 'fresh air' and 'screen' BUT NOT GETTING IN THE CAR STRAIGHTAWAY. Maybe use the time to scrape off any frost or snow, but don't leave the car unattended (obviously). Temperature setting is irrelevant as the car won't warm up for quite some time in this weather, but like this, the screen should not mist up. Once the car's been running for a minute and the air's moving nicely, you can get in and be on your way fog-free. IME, anyway...

Ok, thanks

I'll try that.