Fog/mist windscreen

[jackcramerr]

I have noticed that my windscreen gets foggy. This never used to happen. A.C. does very little to fix it.

Is it possibly caused by the new non Lexus windscreen? How can I fix this as it affects driving at night time.

[NemesisUK]

No, it won't be the new windscreen but quite possibly the way it has been fitted, that is, poorly...

Check the screen surrounds for gaps/dampness.

[VrmmVrmm]

If it's very humid outside and the vents are pulling in the humid air then it condensates straight away on the cold windscreen....switch on fan boost and up the temp a little once screen is warmer you can back off with both boost and warmth...also worth recirculating cabin air until the car warms  the cabin air a little.  It happens to me very occasionally if I leave the car out for a long period on a misty muggy morning or evening.  I garage my car every night never left out in all the years I've had it since new...so once in a blue moon it might happen to me.  Leave A/C off until it settles as the cooling will only keep the screen cooler on the inside and again exacerbate the condensation effect.  If that doesn't cure it then as others have suggested you may well have a poorly fitted screen.  Now Autumn has arrived cooler and wetter...could be the reason. I think there's a smoke test than can be used to fill the cabin and see does it leak out with all vents closed.  Worth considering too that you may have a leak elsewhere bring moisture into the car and its staying there...worth checking for any damp carpet and any damaged rubber seals.

[NemesisUK]

Was this fogging never used to happen, I'd double check the fitting of the new screen.

Having the a/c on permanently will help as the incoming air will be dehumidified. 

[Toothy]

Seals on cars, no matter how well built they are, will degrade over time allowing moisture in.
I suggest getting some drying bags to remove excess humidity. Running the aircon should quickly clear any mist on the inside as it's dry air.

[jackcramerr]

Air con was not removing the mist. It reduced it.

Autoglass are coming to see it. What should I be aware of?

[Linas.P]

Not sure if you have same problem, but that was one of the signs before my A/C "died" - just need find leak and re-gas.

At first I realised it does not demist windshield even the air was relatively cold (I don't go crazy cold ~21.5C), stage 2 - it actually started misting windows even more, before actually stopped working altogether.

[jackcramerr]

Hi Linas

Got AC service done from Lexus. I think I still get the mist. Will confirm it tonight.

I asked Lexus if they do windscreen change and they said they use companies similar to autoglass.... so there is no original lexus glass? 

I am worried about quality of glass.

[rayaans]

9 minutes ago, jackcramerr said:

Hi Linas

Got AC service done from Lexus. I think I still get the mist. Will confirm it tonight.

I asked Lexus if they do windscreen change and they said they use companies similar to autoglass.... so there is no original lexus glass? 

I am worried about quality of glass.

There is original Lexus branded glass but it won't be cheap. Asahi glass corp make the original windscreen and its highly unlikely you'd be able to get it here - it'd have to be ordered in.

I wouldn't be worried about the glass itself - that won't have any effect on why the windscreen is misting.

Back in 2001, my VW Passat did the same thing out of the blue, basically misting the inside of the windscreen permanently - turned out it was a heater matrix that had gone so worth checking that out.

 

[Linas.P]

On 10/28/2017 at 5:52 PM, rayaans said:

turned out it was a heater matrix that had gone so worth checking that out.

Now you got me worried... I though it will be simple A/C service for me, but if that is related to something like A/C condenser or heater matrix it might well be expensive and complicated fix.

As for the Glass I agree - the glass itself makes very little difference, only problem can be fitting of the glass.

[rayaans]

13 minutes ago, Linas.P said:

Now you got me worried... I though it will be simple A/C service for me, but if that is related to something like A/C condenser or heater matrix it might well be expensive and complicated fix.

As for the Glass I agree - the glass itself makes very little difference, only problem can be fitting of the glass.

Back in the day the heater matrix on that Passat wasn't too bad to get done. Nowadays its probably a different story. 

The fitment of the glass might cause mist on the inside, but it shouldn't be there permanently. 

[Linas.P]

Yes.. that is why I suggested to check re: ventilation and A/C.

Obviously, misting is combination of factors i.e. difference in glass vs. air temp + humidity. The reason A/C removes misting is that it blows dry air,  regardless of temperature delta it cannot mist the window. In my case I still have original glass, but the issue was clearly A/C related - it was blowing very humid air (even when it was cold). It seems same for jack - if A/C does not remove mist completely it kind of indicates that air coming from A/C is not "dried" sufficiently to demist windshield. Old fashion option to demist window is to crank the heat-up... that is what I am currently doing as I cannot find the day to visit A/C service.

If A/C is blowing cold air, but it still mists windows and yet A/C performance check comes as OK - I would suggest checking A/C drain, maybe it is stuck or something (though I would expect Lexus to do it anyway and unblock/advise as required).

[jackcramerr]

Paid 60 pounds to Lexus for it so I hope they have done their checks as suggested by rayaans and Linas...

I will see the report they send me if it says anything.

[Linas.P]

Which Lexus does it for £60? I was quoted £99, but opted not to do it... That is because as sad as it sounds I don't trust Lexus to do all the checks e.g. actually finding leak and properly diagnosing the issue before re-gas. I prefer to go for A/C specialist where I can watch them doing it, the only problem I have no time during working days and they do not work on weekends or after business hours, so I basically need day off just for A/C.