Foggy windows!

youknowwho

Has anybody got tips to stop the inside of the windscreen from fogging up? Every morning and evening when I return to my jeep there is a lot of condensation which takes ages to clear just using the fan. Have tried halfords demister before but it didn't work.

Stavros Murphy

There's thread after thread on it if you do a search. Synopsis - seals, dehumidifier, replace pollen filter, spuds.

Supergurrier

Your problem is moisture inside the car/windows themselves.

Best thing to do is give the inside of the windows and the rubber seals on the doors a good clean (buff+dry windows with newspaper) and make sure the door jambs/rubbers seals are all dry

Apart from that just make sure and run the heater in car for 10 minutes on hot beforehand to get rid of any moisture in it to ensure your hard work isn't undone once you stitch it on again.

Check condition of pollen filter

Possibly get afew of the silica dessicant bags and leave them under your seats or mini dehumidifiers based on the same principle (pound shop job)

Should do it

Stinicker

youknowwho wrote: »

Has anybody got tips to stop the inside of the windscreen from fogging up? Every morning and evening when I return to my jeep there is a lot of condensation which takes ages to clear just using the fan. Have tried halfords demister before but it didn't work.

Run the Air-Conditioning, it will clear it in a very short time compared to a normal heater fan.

Popoutman

And don't be afraid to run the air-con as a matter of course during the winter - precisely because of the air-drying capability.

It's prudent to run that aircon for maybe 10 min a fortnight to ensure that the seals in the aircon system get the oil necessary to stop them deteriorating. The refrigerant contains a lubricant type of thing that will keep all the seals in good nick. If the aircon isn't used over a period of time then it is more likely for the seals to perish and refrigerant to be lost to the atmosphere. It's far cheaper to run the aircon once in a while and take the minuscule fuel efficiency hit than to have to pay early for an early or more frequent aircon system recharge or overhaul with leaky seals.

Also worth noting though that the aircon will not dry the air once the outside temp drops below about 4 degrees as ice would otherwise form on the condenser matrix blocking it.

phelixoflaherty

Is it not a case of warm air holding more water vapour from ones breath and when you park the car the air gets colder and the water gets deposited on the glass.

Therefore turn air to cold and open window about a minute before you park.

Jesus.

Use a rag

Noccy_Mondy

Jesus. wrote: »

Use a rag

and just clear a tiny circle so you can see out..

coylemj

The glass fogs up when droplets of water vapour in the air stick to tiny blobs of dirt and grease on the inside of the windscreen. Warm water vapour (provided by your breath) and cold glass are especially attracted to one another. Wiping the glass with your hand or any kind of a cloth (usually full of dust, oil from your hand and general dirt) will only provide more crap for the vapour to stick to.

Buy a bottle of AutoGlym glass cleaner, apply it to the glass with a clean, damp cloth, then polish it with a dry cotton cloth, that will get you 90% of the way towards clear glass in the winter. If the water vapour has no sh1t to cling to, your glass should stay clear.

keithclancy

White Vinegar cleans glass very well.

650Ginge

Buy a cheap squeegee. Or a fancy karach
er suction one.

Who has time or money to run their car engine for 10mins before driving away.

Jesus.

Stinicker wrote: »

Run the Air-Conditioning, it will clear it in a very short time compared to a normal heater fan.

Cold air as opposed to hot air? Would that work?

keithclancy

Jesus. wrote: »

Cold air as opposed to hot air? Would that work?

Just with Aircon on and leave the temperature at normal, air conditioning removes moisture from the air, so it won't add to the problem of moisture condensing on the windscreen and makes the hob of removing fog much easier.

Actually in my Volvo it recommends to leave the Aircon on all the time.

Does make a bit difference, with it off it seems to take much longer.

After winter its a good idea to spray the condenser with water, since salt buildup on it can cause corrosion and a leak in your airco system, not super expensive to fix but avoidable and a pain in the ass.

Jesus.

Clancy, I thought Air Con was simply cooled air for when its hot outside? Are you saying that Air Con can be warm air too? I thought warm air was warm air. Are there two different systems in cars instead of just one?

Excuse my ignorance pal, I just never really understood the settings on my heater!

corktina

Turn on the aircon, turn off the recirc, turn up the fan, make sure you have selected "screen"

Truckermal

corktina wrote: »

Turn on the aircon, turn off the recirc, turn up the fan, make sure you have selected "screen"

I have that same problem but no air conditioning. .

corktina

SAme method should work eventually for you paupers with no aircon :-)
I used get a lift to work with a colleague and each morn he would spned the entire journey mopping the screen but had the fan off and the vents shut.

Days 298

Look for a source of moisture. Once I stopped keeping my gym shoes in the car the problem disappeared.

Stavros Murphy

I'm always a bit baffled when someone pulls up alongside at lights, every window in the car fogged to fcuk up, peering out a little hole cleared in the windscreen, wipers battering away ninety to the dozen. There's loads of them. Personally, would I fcuk drive a car like that, you can see nothing, it's dangerous for you and everyone else, and worse still, it's easy to fix. If I had a car that even vaguely fogged it's windows I'd jam it with dehumidifier tubs till I found the cause. "Seeing out" is kind of a must-have for driving a car.

Zoney

Find the glass in our car fogs up very easily these days, but can drive off and stay fog free just having heat at max and fan at max for the first 5 mins of the trip. For demist, the same but with air con on. Rear window heater helps too if particularly foggy. I think air in car being cold and people breathing is enough to fog the windows?

Cantona's Collars

I think this horrible damp weather is a lot of the problem,I use the aircon to clear mine but anyone else in the car complains with "turn on the heaters,it's cold" - I don't care if it is,I can see where I'm going which is more important.

corktina

can you not adjust the temp but have the aircon on? I do

pa990

zerks wrote: »

I think this horrible damp weather is a lot of the problem,I use the aircon to clear mine but anyone else in the car complains with "turn on the heaters,it's cold" - I don't care if it is,I can see where I'm going which is more important.

Turn the temp to hot, then press the a/c button.


People seem to think that a/c is only for the cold setting.

Mena

Hmm, am I the only one that never turns a/c off? Use it for heat and cooling. Fogging never an issue.

Noccy_Mondy

Gotta love Ford's quick clear windscreen, foggy windows no more!!

Popoutman

The humidity control of air conditioning is a side effect of the cooling of the incoming air, and in most car ventilation systems, that air can be heated again as normal.

In other words the conditioning of the air is independent of the temperature control of the incoming air.

I never put my climate control on "Econ" setting, I run it year-round and I don't find that much of a problem with fuel. I need the drying as I tend to carry kayaking and mountain bike gear in the car a fair bit and that wouldn't help the dampness levels much if I didn't have the dry air coming in all of the time.

Cantona's Collars

pa990 wrote: »

Turn the temp to hot, then press the a/c button.


People seem to think that a/c is only for the cold setting.

It clears mine quicker on cold,usually I'm in a rush so need the window clear instantly.

Pinch Flat

Turn on ac to warm, turn off recirc. My focus fogs up in no time when recirc is on

dickwod1

Try this stuff from Halfords or similar works for me!

Hal1

I have two of these in the back of the car. Get them in homestore and more, but did see them going for cheap on ebay.

Jesus.

pa990 wrote: »

People seem to think that a/c is only for the cold setting.

That's what I thought. I don't get it.

Hal1

It's air conditioning. So selecting the a/c button will set the temp at whatever the setting is set at. Low setting cold air, high setting warm air. Air con - something I should have but don't .

Renegade Mechanic

Jesus. wrote: »

That's what I thought. I don't get it.

Air Con cools the air the same way a fridge does. But it is also a de-humidifier. That pool of water you often see under the car is the moisture taken from the air as it passes through the heat exchanger, collects and goes,through a pipe to the outside. "Dry air" hitting the,
windscreen will take the moisture on it, clearing it quickly.

StickyIcky

Air Conditioning doesn't mean 'cooling the air only' air conditioning means adjusting the properties of air, generally temperature and humidity, but sometimes disinfecting too with filters etc and temperature wise it can be coiling or heating.

In short air-con units can heat air just the same as they can cool air. The drying of the air though I thought really only works when the air conditioning unit cools the air and as the warm air passes over the cold coils the cooling air compresses and it's moisture condenses on the cool coils being extracted from the air.

Renegade Mechanic

Also, imho the very best thing to prevent fogging is below.



http://www.rainx.com/product/glass-and-cleaners/rainx-anti-fog/#.UtxQJKBFAm8

Definitely worked in my old Astra.

MetzgerMeister

I clean and polish the inside of my windows once a month and although they do fog up, it'll be cleared in seconds. Here's what I do:

1 - using an applicator pad covered in TurtleWax glass cleaner, I wipe the glass. The applicator pad is so that as you rub, any dirt is getting soaked back into it instead of just being moved around.

2 - Then I use an old, rough t-shirt (soft ones won't absorb liquid) and dry the glass cleaner off completely.

3 - run the heater at 22 degrees so that it's both warm and cold air drying the glass.

4 - Apply AutoGlym glass polish using a meguiars evencoat applicator pad.

5 - Heater on again to dry the polish to a haze

6 - Buff polish off with a microfibre cloth.

7 - Admire perfectly clear glass.

If you're going to do this, do not ever use a cloth or anything other than the heater to clear the windows. A lot of people say "air conditioning" when they actually mean just the fan. Actual air con is the really cold type of air that comes from pressing the "snowflake" button. This does help to clear foggy windows but it will only come back even worse.

The best thing in my experience is to use 22 degress and above to clear the windows and leave it on at the fan's weakest setting to keep them clear. Also have it set to bring air in from outside, do not recirculate air in the cabin. Only do that during the summer with the actual air-conditioned air to save petrol.

Renewing your pollen/cabin/microfilter also helps.

Noccy_Mondy

Exactly as MetzgerMeister said, I find that about 22 degrees and set to auto works fastest to clear all the windows, side and back included.

Jesus.

Renegade Mechanic wrote: »

Air Con cools the air the same way a fridge does.

So how then can it also be "hot" air?

I'm guessing my car has two systems in the heater, not just one?

Jesus.

StickyIcky wrote: »

Air Conditioning doesn't mean 'cooling the air only' air conditioning means adjusting the properties of air, generally temperature and humidity, but sometimes disinfecting too with filters etc and temperature wise it can be coiling or heating. In short air-con units can heat air just the same as they can cool air. The drying of the air though I thought really only works when the air conditioning unit cools the air and as the warm air passes over the cold coils the cooling air compresses and it's moisture condenses on the cool coils being extracted from the air.

I gotta say, for a bloke who grew up when there was just hot air and cold air in cars cabin systems, this thread is as complicated as a NASA aeronautical space program

Renegade Mechanic

Jesus. wrote: »

So how then can it also be "hot" air?

I'm guessing my car has two systems in the heater, not just one?

That is the question unfortunately:o
I put my own car to 23 degrees in 6 degree weather. I know the AC worked because I could hear the pump engaging and putting load on the engine. Im almost positive the air is passed through the cool heat exchanger, being cooled and "dried" before being heated by passing through the engine coolant fed heater radiator (Section of the cabin heating known as "the heater matrix"- where a flap dictates how much air is blown through the radiator, heating it, and how much is blown through a bypass, keeping it cool).

Satanta

I got this stuff before after seeing it recommended in the detailing forum. It's very good.

http://www.cleancar.ie/car-pro-fog-fight.html

_Kaiser_

I just leave the climate control/aircon on all the time regardless of the weather and adjust temperature as needed. Never any problems that 45 seconds on maximum won't clear.

Anan1

Jesus. wrote: »

So how then can it also be "hot" air?

I'm guessing my car has two systems in the heater, not just one?

The air conditioner cools and dehumidifies the air. The heater then heats that same air, giving you warm, dry air. This is why on many cars the demist setting automatically engages the AC.

Jesus.

Anan1 wrote: »

The air conditioner cools and dehumidifies the air. The heater then heats that same air, giving you warm, dry air. This is why on many cars the demist setting automatically engages the AC.

Aah, I see. I read on here before that the first thing you should do is turn off the "circulate" setting which comes on automatically when you're trying to demist. Is that correct?

keithclancy

Jesus. wrote: »

Aah, I see. I read on here before that the first thing you should do is turn off the "circulate" setting which comes on automatically when you're trying to demist. Is that correct?

Yes, otherwise your just recirculating all the humid air already in the car and turning your car into a make shift steam room

astrofool

Also a Ford here, press the "Max" button and have clear windows about 30 seconds later

Other than that, never have the AC off, just set the temperature as desired (18-22 depending on the month).

Anan1

keithclancy wrote: »

Yes, otherwise your just recirculating all the humid air already in the car and turning your car into a make shift steam room

Depending on conditions outside the car may demist faster with recirc on - don't forget that the AC is still drawing moisture out of the air that passes through it.

Truckermal

Satanta wrote: »

I got this stuff before after seeing it recommended in the detailing forum. It's very good.

http://www.cleancar.ie/car-pro-fog-fight.html

Cheers does this clean the glass too or does it need to be polished first?

SleeperService

Anan1 wrote: »

The air conditioner cools and dehumidifies the air. The heater then heats that same air, giving you warm, dry air. This is why on many cars the demist setting automatically engages the AC.

Its a smart feature, I imagine it causes consternation for the more miserly people who see every second headlamps or aircon are turned on as a wasted micro cent.

Chimaera

Recirculation is a terrible idea unless you're in an environment where the outside air is unpleasant. It takes the air from inside the car and passes it back around through the heater so any moisture in the air is kept.

A lot of cars are set up so that turning the ventilation system to the windscreen setting will automatically disengage the recirculation system if it's been engaged. Except in the rarest of cases, outside air will be less humid than the air inside the car.

Standard ventilation in a car just heats the air coming in from outside. At its coldest setting, it draws air at the outside ambient temperature and pumps it in (which is why it's terrible on a warm summer's day). Turning up the dial allows it to be warmed to a temperature above ambient. It will not change the moisture content of the air. Heating does change the relative humidity though which is why warm air at the same moisture content can absorb more moisture from the surroundings than cold air. In these systems, the heat is provided by a heat exchanger which uses warm coolant from the engine to heat up the air. This is why you're waiting a few minutes after starting the car before you get heat.

Air conditioning has the same warm air heat exchanger as the standard system, but it adds in an additional heat exchanger which can actively cool the air and bring it down to a temperature below ambient. One consequence of cooling air is that some of the water vapour held in it condenses out and the air gets drier (this isn't the primary design goal in automotive aircon systems, but it's a useful side effect of cooling the air). If this air is now heated back up, it can absorb a lot more moisture. Even without heating, the removal of the moisture from the air allows it to absorb moisture from the 'screen and work at demisting.

Climate control as fitted to a lot of modern cars is an air conditioning system fitted with a fancy controller that allows it to maintain the temperature within the vehicle at a particular setpoint without intervention from the driver. The defrost setting on these systems usually turns the aircon up to its maximum coldness setting to remove as much water as possible from the incoming air before heating it back up to achieve the desired temperature setpoint within the vehicle. Outside of this setting, the system will try to reduce the aircon compressor duty as much as possible to improve fuel efficiency.

Why are cars fogging up so much at the moment? It's cold and humid weather out there. Even if your car interior is bone dry, you're going to end up with foggy windows some mornings. What's happening is that your car's bodywork is getting very cold overnight as temperatures drop. Once the temperature of the car reaches the dew point of the air, it'll get foggy. The problem is that even when the air outside starts to warm up again after sunrise, the car's bodywork lags behind so it stays foggy, especially inside the windows. Another thing that'll be happening is that the moisture particles are aggregating and forming larger droplets which take longer to evaporate off than small ones. So even when the air temperature gets back over the dew point, you're stuck with lots of big moisture particles that will only evaporate slowly.

How to defeat this?

The best option is store the vehicle in a garage, preferably a heated one. Not an option for most of us though.

Make sure the inside of the windscreen is spotless. Dirt particles will serve as nucleation sites for moisture droplets. A clean screen will be slower to fog up and the moisture particles that do form will be smaller. Avoid any cleaners that leave a hydrophobic residue i.e. anything that causes beading. We love beading outside because it makes the rain bead up and fly away but inside that beading means it takes longer to demist. I've found a 50/50 solution of isopropanol in water works very well here. It's an excellent degreaser and leaves no residue. Use kitchen towels or a soft cotton cloth for cleaning. Newspaper is a no-no - the ink comes off and leaves a residue on the glass. Vinegar will also leave a residue, plus it stinks. Residues are bad. If your 'screen is very dirty, it might take a few goes to clean it.

If you find you are getting fogging on days when other cars are not, then it's time to check for water inside the car. Check door and boot seals for leaking. If you have a sunroof, check the seals there too, and the water drain tubes. Check the spare wheel well: it's a low point in the boot and if you've thrown wet stuff in there at any stage, it'll collect water. Check your pollen filter: on some cars it can get wet and this will humidify any air entering the cabin. Check the area around the intake for cabin ventilation: again any water here can humidify the air entering the car. Check for damp patches in the car: maybe you left a wet coat on the back seat and it didn't dry out, or the wet bag of coal you brought home last night left damp in the boot. Some cars have known issues with water entry: check if yours is one and see if there's a solution.

If you find damp in your car and fix the cause, then using a dehumidifier or silica gel capsule can remove the excess dampness for you. These will do no good if the fogging is due to atmospheric moisture, it's just a waste of money as all you're doing is pulling moisture from air that has effectively a nearly infinite supply of it.

Chimaera

For anyone with an interest in the finer theoretical points of air conditioning and humidity control, this page is a good start: http://en.wikipedia.org/wiki/Psychrometrics