I have just returned from a school run, the first of many I am sure, during the colder and wetter weather. I had the experience of having to pull into the side of the road only 100 metres from home as the windscreen had suddenly fogged up in spite of the blower being on max and the air directed onto the windscreen (Climatic air conditioning).

This will be my first Autumn/Winter driving my Octavia 1.9tdi Ambiente estate and I wonder if some of you old hands have some tips for getting going in the morning in the poorer weather? This is my first diesel car, my last vehicle having been a VW Passat 1.8 petrol estate which I had for 12 years.

Close all the passenger air vents and make sure the air con is switched on and not in Econ mode. The reason you need the air con switched on (yes I know its coming up to winter) is it acts as a de-humidifier.

When I had a 1.9TDI MK I Octy it took ages for the engine to warm up and provide hot air out of the vents. I don't think the MKII 1.9tdi has electric heaters in the air con circuit and being near as damn it the same engine I think that you're probably blowing cold air onto the windscreen.

Thanks for the reply mikel543.

My Climatic does not have Econ, but true enough I did not have all passenger vents closed so perhaps not enough air was getting to the screen. Certainly the air con was on and the temperature control was set to maximum but the engine takes an age to warm up (total miles to date just over 3000) and cold/luke-warm air was certainly being produced for most of the trip - a round trip of only about six miles but on reasonable A roads. I feel that the old Passat would have done better, but perhaps that would be due to the petrol engine?

I noticed on another thread that adverse comments were being made about the heated rear screen and I would agree with them. The other evening no real impression was made on the mist with only two people (including myself) in the car in a distance of about two miles in slowish traffic.

Perhaps I should start the engine early and hope that it has warmed up a bit before setting out? I have always been under the impression that this is bad for the engine.

I thought that the heating system would have been more efficient in a vehicle basically designed for harsher climates than the UK. But then the driver's door seals on the Passat froze regularly to the body work and the lock mechanisms froze solid on many occasions - I hope this will not happen with the Octavia! We shall see!!

When my wife bought her Fiat Doblo it was the first diesel that we had. Members of the Fiat forum told me that slow warming up was the downside of a modern, high efficiency diesel engine. I have only had the Octy since August, so little need for demisting/heating. What I will say is that it seems to warm up in about half the time that the Fiat one does!

Diesel engines take a lot longer to heat up than petrol engines on a cold morning because there is more cold air per stroke taken into a diesel engine than on a petrol engine with equivalent capacity, the extra cold air provides a cooling effect in the cylinder.

When I had a 1.9TDI I used to start it and leave it on my drive until it had warmed up sufficiently to clear the ICE, snow, mist etc... usually about 5 mins. I used to find that if I wiped the mist of the windscreen it would just mist up again almost straight away, even using one of those special cloths.

A lot of people would advocate against this as it causes carbon build up in the cylinders and on the valves. I always planned to get rid of my 1.9TDI when the warranty ran out so I took as short term view on it.

we bought cheap wind shield covers for winter use for the exterior screen when icing conditions forecast x for the interior the only option is a good

clean chamy cloth as smears are a nuisance

my 2.0 tdi OKT 140 with climate control can take a few km's to kick in,the fabia with a/c is worse,sometimes taking 10 plus km to warm up

Sure I read on here diesels only warm up properly when under load.

Hence just leaving them sitting on the drive does take an eternity for them to warm up

The Air Con dries the air, so the engine heat is less important.

I think what it is, is that the residual damp air in the system is blown onto the cold windscreen and condenses. It then takes a bit for the Air Con to remove the water, and start drying the screen.

Don't think there is much you can do, other than wait for the screen to clear (or use a cloth).

Don't think there is much you can do, other than wait for the screen to clear (or use a cloth).

Or fit a webasto or kenlowe diesel heater as per the kenlowe thread that is on here, not a cheap option but very very handy

I believe the Octavias that are sold in the colder climates have electric heaters built into the heating system. These provide heat straight away on start up so get around the engining warming up issue. Also very cold countries have heaters in the engine that warm the engine up before you start it (you plug your car into the mains power when you park it up). I have seen little electric fan heaters that plug into the cigarette socket in the car and have always wondered if pointing one of these at the windcreen would help with clearing it.

The only other suggestions would be not to put the air straight onto the windscreen when you get it. Allow a minute or so for the moist air left in the system to be pushed out the passenger vents then turn the drier air onto the windscreen (I believe my VRS does this automatically-I have dual zone climate with a special front window clearing button, gives full power on fan, full heat and air con on,- so when I press the special button it blasts out briefly from the passenger vents before turning on to the screen).

Thank you for your replies. As I thought there might be, a range of ideas and arguments - pros and cons!

GriffoVRS has a point that seemed logical from this morning's experience - residual moisture condensing on the screen. I found that I could see for only the time taken to cover the 100 metres and then suddenly the screen was fogged over. In the past I have used kitchen paper to clear condensation, this also leaves few smears. I'll keep a roll handy next time.

I think that I will also try letting the engine idle on the drive before setting out and see if that helps.

Again, thanks for your thoughts.

PSM

I spotted your reply after posting my comment. The fact that your air con goes into a special routine must be indicative of the best route to follow. This must be tried on my next cold start!

Thank you for that.

I think that I will also try letting the engine idle on the drive before setting out and see if that helps.

.

My point was that I understand it is better to get driving asap rather than letting it just idle

Hi lozgti

I accept your point, that is what I have always been taught but if I have to keep wiping the screen as I go through the road-narrows on our road, I might be more of a danger to other people than usual! If I lived elsewhere I wouldn't be so concerned and I would definitely just get on the road and go.

i have a screen clear function in my vRS but i find it does the same sometimes, get to the bottom of the road and it steams up, give it another 10 seconds or so when the Air con works properly and it clears, i think its just that initial lack of air con as the compressor charges the system

When you set off put the air con on and set it to the minimum, not to heat.

get it out at the weekend, drive for about 20 minutes with the air con on to suck in the mositure and have it on hot heat at the same time. after 20 minutes turn off the air con but leave the heat on for about 30 minutes and still carry on driving, this should then have the whole car dried out and when you next take the car for a drive shouldnt mist up.

turn off the air con but leave the heat on for about 30 minutes and still carry on driving, this should then have the whole car dried out and when you next take the car for a drive shouldnt mist up.

Surely this will just re-humidify the air with the water vapour in your breath:confused:

nope not as bad as its probably misting up now, done this on a few cars including this one when the misting gets bad. solves it for a while, keeping the windows clean with something like AG glass cleaner helps a bit too.

I just open the drivers window about 2 inches before moving off, stops it misting up again

In theory if you cooled the temperature in the car before you stop in the evening then this should help in the morning. I have never tried this but the theory would be that the colder air in the car would contain less mositure than if it was warm and hence you would get less condensation forming. The best way to do this would be to set the air con temp to minimum as this would give you dried cold air in the car. The only problem with this technique would be that you get a bit cold for the last mile or so of your journey!!!!! If anyone has done this or does do it then let me know if it works!!!

In theory if you cooled the temperature in the car before you stop in the evening then this should help in the morning. I have never tried this but the theory would be that the colder air in the car would contain less mositure than if it was warm and hence you would get less condensation forming. The best way to do this would be to set the air con temp to minimum as this would give you dried cold air in the car. The only problem with this technique would be that you get a bit cold for the last mile or so of your journey!!!!! If anyone has done this or does do it then let me know if it works!!!

Thats what we like a volunteer:)

A volunteer is worth a thousand pressed men but easier to find the thousand men to press than the 1 volunteer:smrbow:!!!!!!!!

Just a thought, if the vehicle has a pollen filter check its not damp or blocked.

Just a thought, if the vehicle has a pollen filter check its not damp or blocked.

Or water leaks allowing the carpets/underfelt to get wet and retain moisture ? IIRC There have been a thread or two about leaks causing demisting problems in winter.