sierrafery
Well-Known Member
Hi, based on the diagram i must say that as long as a part of it is working there is certainly a crack somewhere just that you dont see it cos it's only one circuit which feeds the demister, i think you should remove the seal to see the bottom lines where the wires are connected cos there is the problem... i've never touched one to see how it is
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Graculus
Well-Known Member
Do you have / know anyone with an infra-red camera? it will identify the area of any break quite easily.
The picture below is an example, whilst this was demisting 'acceptably', the arcing across the damage was knocking out the DAB reception when the heated screen was switched on.
I think you can still get conductive paint to repair damage to heating elements.
The picture below is an example, whilst this was demisting 'acceptably', the arcing across the damage was knocking out the DAB reception when the heated screen was switched on.
I think you can still get conductive paint to repair damage to heating elements.
Hi how will it find the broken element is half of the elements are not working? Can the camera light up all the elements and only show the broken bit as not brighten bit? Bit confused.
i think the crack is in the middle somewhere where I am unable to point out. If it was inside the seal it would have stopped working completely. My guess!!
Graculus
Well-Known Member
As all the element is slightly resistive (otherwise it wouldn't heat), it'll show heat up to (or very close to) the point of the break, you just need to check both the positive and ground sides, using a LED torch will help if you hold it at about 15-30 degrees to the glass as it'll highlight any edges where the damage has broken the printed element. If the break was in the middle, then elements either side would be working so you would just have a band where the screen wasn't clearing, for half the tracks not to be working, then the damage is more likely at the areas where they connect to ground or positive.
sierrafery
Well-Known Member
You are guessing wrong IMO... all those curved lines are connected to the two base lines which are feeding them and if one of them is cracked at the half the demister lines connected to that lower side will not work.
I made a rudimentary diagram with only 4 lines just for example to show that if there is a crack in one of the base sides under the seal where the power wires are connected the upper lines which are after it will not have power , the crack can be on the earth side too i hope it makes sense to you.... though there can be hairline cracks in all the non working lines too but not so likely
Thank you so much. Much appreciated. It makes more sense now. The garage the car is currently with other problems could not find the issue. I have suggested them as here. Thanks again.
Thanks so much. I guess you are talking about the baseline. I will have a look tomorrow.
NPG
Well-Known Member
Alternatively you can try using a compass while the heater is on and take note when the needle stops deflecting, which is where you have no current flow.
Graculus
Well-Known Member
Yes, up to a point, if the track is a metre long with a break in the middle, none of the track will be consuming current as the circuit is not complete, so the compass would stop deflecting along the entirety of the metre long track. Whilst there would be voltage up to the point of the break, it needs current flow to deflect a compass needle.
