Replacement windscreen advice

[TrundleFly]

Hello all

A big crack has appeared in my windscreen so I am getting a replacement. This is through insurance and they use National Windscreens.

The optional extra code for my windscreen is:

4GM = Laminated windshield with metal layer, with sunshield and viewing window for vehicle identification number, heated

I have some questions that I'm hoping you might be able to help with:

1. What is the best way of ensuring I get the right screen? Is there something I can check on it when they turn up to fit it?

2. Nowt to do with replacement, but how does the "heated" part work for the windscreen? We also have a Ford which has a heated screen and you can see thin metal wires in it and this is what comes on when you press the defrost button. In the Audi though it just seems to turn on the fan. How do you activate the heated bit and how does it work as I can't see any lines like in the Ford?

[mb]

When I had to have my Golf screen replaced I just checked & double checked they understood it should have blue glass & rain sensor as there was a spate of R32s getting given green glass. I also asked the chap to check was the correct screen before cutting the old one out which he was happy to do.

Autoglass were very helpful & did a great job. No idea how your heated screen works - is there a button apart from on the AC or maybe the windsreen has been replaced before with the non-heated variety ?

[TrundleFly]

All seems sorted. Took it to the windscreen place as they wanted to have a look at it and they reckon they have an Audi one in stock so it is being replaced next week. They were very helpful and seemed to know what they were talking about.

Apparently the heated screen works by having a strip running all around the outside where the seal is and that is what gets heated, rather than all over heating that the Fords have.

[IT_S8]

Apparently the heated screen works by having a strip running all around the outside where the seal is and that is what gets heated, rather than all over heating that the Fords have.

The heated screen is a very rare item indeed - Check out this thread to confirm if you have one or not, however your build code certainly doesnt suggest so:

Retro Heated Windscreen - A8 Parts Forum

Regards - Ian.

[mikael]

All seems sorted. Took it to the windscreen place as they wanted to have a look at it and they reckon they have an Audi one in stock so it is being replaced next week. They were very helpful and seemed to know what they were talking about.

Apparently the heated screen works by having a strip running all around the outside where the seal is and that is what gets heated, rather than all over heating that the Fords have.

This is a rare option and I hunted high and low for an A8 which had it fitted, until I found the one I wanted with it on. It seems your local windscreen place is very good, as I had a chip in my one, and I wanted it repaired, rather than replaced, as the windscreen place did not believe it was heated, as you cannot see any wires. I did not want all the agro with convicing peopel to get the corerct screen.

My understanding is that the material between the layers of glass is slighly conductive, and therefore allows heat to build when electricity is applied to it. I don't belive it is just heated around the edges, as the entire windscreen heats up evenly and defrosts very fast in one go. It has been superb this winder, and I'm very glad I have it. Just be sure you do get them to fit the correct spec screen, probably as a special order from Audi.

On the D3 as I have, it is activated either automatically if the outside temperature is below 4 degrees and the Climate Control is set to Auto with Econ mode set to off. There is no specific indication to show the heated screen is on in this case, except if like today it is so cold, a few drops of water smear on the screen from the wiper blade and some steam comes off the screen! The heated screen can also be turned on if the outside temperature is below 4 degrees and you press the demist button on the centre console. Intially the fans will go fast, but if the heated screen comes on, they slow down after about 2 seconds and the defrost button LED begins flashing slowly. The heated windscreen will automatically be turned off after a few minutes and the LED will stop flashing.

Edited January 8, 2010 by mikael

[TrundleFly]

Ian - what makes you say my build number means I don't have it? The build number and it's description is below:

4GM = Laminated windshield with metal layer, with sunshield and viewing window for vehicle identification number, heated

There is another code (can't remember what it is now) that has the same description as above but without the "heated" bit at the end.

I got the desciptions by adding all the codes from my service book into here:

VW Group Option Codes Decoder

For the windscreen place, they said they bought a job load from Audi last year as they were getting rid of them and have the correct one for my car. I'm going to check the heating thing before I take it in as I didn't know how to activate it.

I normally have eco mode on and did notice the other day after pressing my demist button that when I looked down again later it was flashing and wondered why. I'm going to check it again to make sure so I know what to check for again after the new screen goes on.

Thanks for all the help, will let you know how it goes.

[TrundleFly]

I also found this, which is a full list of the option codes:

http://www.vaglinks.com/Docs/Misc/Audi_PR_OptionsCodes.pdf

I think these are the two different types of UV insulated, one heated and one not:

4GM laminated windshield with metal layer, with sunshield and viewing window for vehicle identification number, heated

4GN laminated windshield with metal layer, with sunshield and viewing window for vehicle identification number

[mikael]

Ian - what makes you say my build number means I don't have it? The build number and it's description is below:

4GM = Laminated windshield with metal layer, with sunshield and viewing window for vehicle identification number, heated

There is another code (can't remember what it is now) that has the same description as above but without the "heated" bit at the end.

I got the desciptions by adding all the codes from my service book into here:

VW Group Option Codes Decoder

For the windscreen place, they said they bought a job load from Audi last year as they were getting rid of them and have the correct one for my car. I'm going to check the heating thing before I take it in as I didn't know how to activate it.

I normally have eco mode on and did notice the other day after pressing my demist button that when I looked down again later it was flashing and wondered why. I'm going to check it again to make sure so I know what to check for again after the new screen goes on.

Thanks for all the help, will let you know how it goes.

If you use the demist button, it automatically turns the eco mode off, so the heated screen will then work. If the LED on the button was flashing, the heated screen was definitely working.

I have played around with the different settings, as sometimes I want demist on, but don't want the air-con to be on, as it fogs up again once the air-con is turned off in eco mode. If you don't need the heated screen on when demisting, you can turn on demist, and then turn Eco back on, and it will still run the demist fans, but will not run the air-con, or the heated screen. If you want the heated screen on, you have to leave Eco off!

Edited January 9, 2010 by mikael

[TrundleFly]

Cheers mikael. You'd think they'd have covered this branch of astro-physics in the manual...

[mikael]

Cheers mikael. You'd think they'd have covered this branch of astro-physics in the manual...

You are right, the manual does not cover it in enough detail, and being so rare, nobody in any of the dealers I have been to knows anything about it either!

One other thing I have noticed is since I upgraded my MMI software to the latest (5570 I think), If you have Eco mode on before turning on the demist function, Eco mode will be turned off automatically, but will be switched back on if you turn the demist function off. Before the upgrade, Eco mode would be left off, even when turning off the demist function, so you would manually have to go back into the MMI and turn it on again, if you wanted to have Eco mode back on.

[TrundleFly]

The screen has now been replaced with a genuine Audi one so I just need to wait for some more ice to form to make sure it all still works OK.

I called Audi before and they said the screens are the same and the "heated" part is part of the car rather than the screen i.e. it uses the same UV insulated glass screen as the "non-heated" cars.

I'm actually hoping for some icy weather now to confirm it all still works.

[mikael]

Good to see you update on this. It is interesting, as it would seem then that the Laminated windshield with metal layer is simply electrified when it heats, and on cars without the heating, the circuit and control module to power it up are simply not installed?

[TrundleFly]

Yeah that's what it sounds like from the guy I spoke to in parts at my local Audi dealer. Once I've tried it out with the new screen on I'll let you know. I tried the demist button earlier and it was still doing its flashing thing but there was no ice on the screen for me to be able to confirm.

[TrundleFly]

Just a final post to confirm that the windscreen heating does indeed work fine after the replacement. It's great having a new screen as well as the last had a few chips. Also nice to discover through all this that I do have a heated screen as I didn't have a clue before.

I think that the lesson is - font screen heating, low temps and chipped screens do not sit well together. Even though in my case the chips had been "repaired".