Rear Demister - Lines not working

[mpc]

I have noted that the centre of the 2 top lines of the rear demister on my 61 plate C250 estate are not working, all the lines below and the 2 vertical lines are working but the 2 between the vertical lines at the top are not?
Any Ideas if this can be fixed?

 

[Trickythemerc]

Could be damage caused by the removal of dealer rear window sticker. As for repair I would think not very likely, unless there is some sort of brush on stuff available out there.

 

[markjay]

If the heating element wires are glued on the inner surface of the rear windscreen, then it can easily be repaired. If it's inside the glass, then it can't be easily fixed - but then it would not have gotten damaged in this way in the first place....

 

[markjay]

Granville Rear Heater Repair

 

[markjay]

What you will need to do is use a multi-tester set to Resistance then look for the point along each wire's route where continuity is lost.

Use Cellotape above and under the wire to ensure that the compound stays on the wire line only.

But as said this will only work if the demister wires are glued on top of the glass' surface, not embedded in it.

And yes it's very common, either due to careless removal of dealer/garage sticker, or due to closing the rear lid on bulky protruding object which then rubs against the glass.

 

[John N]

I would have thought that if the 2 top lines of the rear demister were not working then something has either scratched the Element or it has just given up!

 

[mpc]

Could be damage caused by the removal of dealer rear window sticker. As for repair I would think not very likely, unless there is some sort of brush on stuff available out there.

On further inspection I think this is exactly what has happened. I doubt that paint stuff will work as it looks like the break could be a few cm long!

 

[markjay]

Can you post a picture of the affected area?

 

[Dec]

I have noted that the centre of the 2 top lines of the rear demister on my 61 plate C250 estate are not working, all the lines below and the 2 vertical lines are working but the 2 between the vertical lines at the top are not?
Any Ideas if this can be fixed?

That might be normal, on a W202 the top lines don’t clear for some time after the lower lines, my understanding is that the top lines aren’t heated and are for the antenna.

You can inspect the lines for brakes if you have a torch on a smart phone, as seen at night in picture below.

Dec

 

[whitenemesis]

As Dec says, top few lines are the antennae and not heated.

 

[mpc]

As Dec says, top few lines are the antennae and not heated.

I'm pretty sure this isn't the case on my car which is an estate, the ariel for my car is on the roof near the tailgate. I'm happy to be proved wrong tho

 

[mpc]

I'll try upload some pics later today..

 

[Dec]

Maybe things are different on your model, the roof ariel may be for sat nav.

Are there any gaps in the top 3 lines in your rear window?

Gaps circled in picture are normal.


Dec

 

[mpc]

Ok here's some pics of mine

 

[mpc]

This is with the tailgate open so the lines in question are the bottom 2/3 between the vertical lines.

 

[mpc]

This is what I thought was the antenna

 

[Dec]

How are the lines connected together in the Black border areas, are the similar to the below picture?

So, it’s only the lines in Red box that don’t de-mist?

Dec

 

[mpc]

yes, just the bottom 3 lines in the red box don't demist

 

[Dec]

I wonder how the wires are connected at the sides/top.

Dec

 

[mpc]

I wonder how the wires are connected at the sides/top.

Dec

I'll get a pic tomorrow when it's light and post here