My rear window defroster wire grid is toast. I know there is power and ground. I also know that power doesn't manage to get more than a couple inches from the left side - and not even that on some wires.

So I am considering what to do and saw mention of these things (frostfighter.com/clear-view-defrosters-about.htm) which seem able to be powered by existing wires (with some modification).

Sadly, I have not been able to find reviews or much of anything, save from the maker's website. Has anyone had any experience?

Thanks

I just want to follow-up. I installed my Frost Fighter ClearView kit as described above in 2021 and, as reported above, it initially worked reasonably well defrosting the rear windshield in my 1983 242. It is now almost exactly 3 years later and I went to use it for the first time just the other day. Nothing, no effect whatsoever. The defrost switch lit up - meaning not much, of course, except that the fuse was intact. And there is no relay in this model so that is not the problem. I finally got out my meter the next day and went looking around. I initially found no continuity between the + and - tabs (with the supply wires removed, of course). Not a good sign. So I checked continuity for each line between the buss bars and all were intact. I then investigated continuity one grid line by one and discovered that indeed, it was lost on the 6th grid line. And this has to mean that the grid line is not in contact with the buss bar somehow - since there is continuity between the buss bars. Them from the outside, a visual inspection shows several locations along both buss bars where the grid lines appear discolored to a greater or lesser degree - with one of the worst shown here (drive dot google dot com/file/d/1lCJ7oKfmsiW8VwZbVvx4YazB9C5V3Wl1/view?usp=sharing). I am not 100% this is what is causing the problem. But it seems likely. I should point out that this car gets under 2000 miles in any given year and most are NOT in winter when the defroster would be used. I have also never had a fuse blow or any other indication that there might be a problem. The staff at the vendor has been nice in trying to help me figure out the cause and a "fix". But they do say that sometimes the entire grid must be replaced. Even if they would pay for the new parts (which I am sure with their limited 1 year warranty they would not), there is no way I would go through all of this again - plus whatever agony there would be in the removal of the now-dead one. Especially for only 3 years' light service, it just isn't worth the effort. So FYI.

I just want to follow-up. I installed my Frost Fighter ClearView kit as described above in 2021 and, as reported above, it initially worked reasonably well defrosting the rear windshield in my 1983 242. It is now almost exactly 3 years later and I went to use it for the first time just the other day. Nothing, no effect whatsoever. The defrost switch lit up - meaning not much, of course, except that the fuse was intact. And there is no relay in this model so that is not the problem. I finally got out my meter the next day and went looking around. I initially found no continuity between the + and - tabs (with the supply wires removed, of course). Not a good sign. So I checked continuity for each line between the buss bars and all were intact. I then investigated continuity one grid line by one and discovered that indeed, it was lost on the 6th grid line. And this has to mean that the grid line is not in contact with the buss bar somehow - since there is continuity between the buss bars. Them from the outside, a visual inspection shows several locations along both buss bars where the grid lines appear discolored to a greater or lesser degree - with one of the worst shown here (drive dot google dot com/file/d/1lCJ7oKfmsiW8VwZbVvx4YazB9C5V3Wl1/view?usp=sharing). I am not 100% this is what is causing the problem. But it seems likely. I should point out that this car gets under 2000 miles in any given year and most are NOT in winter when the defroster would be used. I have also never had a fuse blow or any other indication that there might be a problem. The staff at the vendor has been nice in trying to help me figure out the cause and a "fix". But they do say that sometimes the entire grid must be replaced. Even if they would pay for the new parts (which I am sure with their limited 1 year warranty they would not), there is no way I would go through all of this again - plus whatever agony there would be in the removal of the now-dead one. Especially for only 3 years' light service, it just isn't worth the effort. So FYI.

The weather has now turned lousy enough in the PNW for me to have had a few opportunities to actually test how this defroster replacement works. And I am pleased to say that it does, in fact, work. I have not tried it against snow/ice yet thankfully. But against cold air and mist it does do the trick. So despite the difficulties I had with the install (much of my own creation, as usual), I can recommend this. FYI

Hi,

Thank you for the update!
I responded to you back in March with this post.

https://www.brickboard.com/RWD/volvo/1678427/220/240/260/280/rear_window_defroster_name.html

I’m pretty sure now it would have been a crazy endeavor.
The two part conductive epoxy, that was going to use, had a questionable age problem of how old it was, let alone applying the stuff.
It fitted one of Arts “footnote definitions” to be a bargain deal!

All of us, in the threads, had a interesting discussion on ideas of what we might try to do.
After watching yours efforts progress along, I made sure I waited.
You probably saved me a lot of grief, Thanks
If and when I go this route I think will try the wagons tailgate one first and not my sedan.


Phil

Phil,

I agree that a tailgate unit might be an easier 1st project since it is flat rather than curved. If possible to easily remove the tailgate and put it on saw horses so the inside is facing up, I would suggest that as well. I always wanted a wagon but never managed to get one. So I don't know about that. Given a flat surface, readily and easily worked upon, installing a frost fighter kit wire-by-wire the way I did MAY be much more doable. However, on the sedan, I think I would avoid it.

The one thing I have noticed with the new defroster kit in place is that when I hit the switch on the dash for the defroster, it can take a period of time for the switch light to go on. Maybe 30 seconds to a minute. Sometimes it comes right on. I am not sure why this might be. In my 1983, I am pretty sure there is no timer or delay mechanism at all - just a plain on/off switch. But so far at least, the light has eventually always come on and the defroster works - far better than it did when broken.

Cheers

Basically spent from 10 am until 3:30 pm (with only minor breaks now and then) struggling with the install of the wire grid from the stick-on kit. I have not completed the connection to power/ground and, of course, have not tested anything yet.

First, the summary conclusions:

1. DO NOT, I repeat, DO NOT try to install the grid lines individually - especially if the window glass is curved as it is on my 240s. I tried everything in my power to get the new wires to follow the old ones in the glass. This is simply impossible to achieve since the new grid wires cannot really be made to follow the way the original lines travel (discussed above). My results are less than ideal and in some places down right awful.

2. There isn't single step in the process that is forgiving. You basically get one chance and one chance only to do something and you must be spot on the very first time. I went slowly - measured twice and cut once and all that. But still managed to get caught off-guard at some points.

3. Baby its hot inside! The instructions insist that you have many hours of 60 degree+ weather to do the install. I would say we hit 70 today but it was only 62-3 when I started. Working in the rear seat, close quarters and all got quite hot - even after I threw a white towel over the window to reduce both heat and glare.

4. Oh my aching knees and back! Good thing I removed the right side front seat from my 242 as I must have had to get in and out of the car about 100 times while doing this. My rear seat has gotten more use today than in the last 20 years for sure. And despite the padding of that seat, it still is quite unpleasant on the old knees. That padding is made for our hindquarters, not our knees.

5. Would I do this again (even if it does work - and I have my doubts)? I certainly don't think so. Installing via the multi-line sheets MIGHT be better than one at a time. But I am unconvinced the results would be that much better. It is true that some of my most serious difficulties resulted from trying to match the original grid lines. This takes far more time in the stick-on process but also in having to custom cut the buss bar components to fit the result. If the results were better, it might be worth it. But they weren't.

Now some details:

1. The release paper used for the inside surface of the grid wires does not provide any visibility. It is too opaque. And so you simply cannot even see the existing grid lines enough to follow them with any accuracy. I say this even after going the extra mile to put 1/8 masking tape over each line in an effort to make it stand out/show through the paper.

2. The release paper has no ability to flex or place the grid wires in any but straight lines. Just forget about anything else. I did not try, as some suggested, to make cuts in the paper to facilitate this. The process is just too difficult to consider doing this as you are sticking things on. And you are severely time limited. From the time you use the special moist cloth to wipe down the window and then dry it off, you have only 30 minutes to complete installing the grid. The instructions were not specific and I was only able to install the horizontal grid wires in about this time. I decided not to sweat the time limit on the buss bars. It would have been impossible to get it ALL done within the time limit even if I had NOT done this line by line.

3. The release paper itself is made sticky. I get this as necessary to make it all work. But from my standpoint, the degree of stickiness is about 3-5 times more than it needs to be. And this makes removing it much more difficult that it should be. I would snip the paper with my surgical snips in the middle of the window and start to pull/tear from there. In many cases the release paper simply would not release nicely and left bits of itself that I had to go back and address. Thankfully, the wires, once stuck to the window, seemed to hold tenaciously enough that the release process worked without pulling them off the glass.

So all in all, the interior release paper is a problem.

4. The buss bars are actually comprised of multiple pieces and need to follow a specific pattern with gaps between them as they cover the grid wires. I am not sure I understand why this is so given that the original defroster just had straight bars with no gaps at all. But the instructions are VERY SPECIFIC. I understand that had I not tried to follow the original grid lines, the pieces included in the kit would have been sized correctly for the grid supplied and most of the pain associated with the buss bars dramatically reduced. But I didn't and so I had to custom cut every piece of the brass strips to follow the pattern. Overall, this makes the buss bars shorter and so the adhesive strip which holds them to the window and the cover pieces must also be custom cut. And at least in my case, this had to be done by sight in the back seat as nothing turned out consistently space to allow for computations and cutting in my shop.

5.The adhesive strips that adhere the buss bars to the window have adhesive on both sides. One is covered with release paper very similar to that used on the grid wires. The other side says 3M on it and is red plastic of some sort. The instructions do not say which side to use where. The 3M side is super hard to start peeling back. I could NOT have done it with the strip in place on the window. I had to fiddle with it using a tweezers in the shop under a magnifier. So I decide to get that side started in the shop, go out to the car, peel off the rest of the red plastic, and adhere that side to the window. I hope that was not an error. But there was nothing in the instructions to clarify it. With the release paper side on the interior, I was able to work with sizing the buss bar strips of brass without fear of getting it stuck in the process by accident. And I could pull back the paper only as far as I needed for the section of brass I was working on at the moment.

6. Above I discussed the "tip" to NOT touch the brass strips of the buss bar and how I had done that to a significant degree prior to the install while trying to make a full scale mock up of the layout. Thankfully, Jeff told me not to sweat that too much and to wipe the brass down with the included wet wipe cloth if needed. Well, there is no way in the world one could manage all the custom fitting and cutting that was required without touching all over the brass strips. So I am glad Jeff chimed in. Again, much of this was due to my decision to try and match the existing grid rather than use the kit out of the box.

Here are photos taken today (drive.google.com/drive/folders/1vK_DWpU3Eqabryaw7nlkl_JzkuOdkMwN?usp=sharing").

You can easily see my general failure to closely match the lines of the existing grid. You can see from the inside how opaque the release paper is and this makes orienting and following the grid lines near impossible - even it the original lines were straight (and they sadly are far from that).

What you cannot see is that it is nearly impossible to avoid kinks in the wires. After putting them down, I tried to smooth them best I could using an old credit card like a putty knife. You cannot over do it as that might break the wire and then you are totally toast. So all you can do is try to minimize these. There is one case that is severely kinked with the wire a bit twisted so you can see a bit of the copper side from the outside. That should NOT be the case at all. But again, the opacity of the release paper makes it impossible to see from the inside what is going on so this was not really apparent until the release paper had been removed. And by that time, the stuff is down and there is nothing you can do.

So, will this work at all once power and ground is supplied? Will it work, but not well due to the minor and major kinks in the grid wires? Will the contacts achieved to the buss bars be good enough after all that handling and cleaning? Will this work but the kinks and uneven spacing cause bad heating characteristics resulting in a shattered window? Only time will tell!

Again, I want to make it clear that I believe that much of my difficulty was likely due to my own decision to try and follow the original grid lines in the glass rather than doing a standard install. Goes to show, as a buddy of mine told me yesterday, "don't give an engineered product to an engineer!" I must plead guilty.

I have included some photos so that folks can see for themselves the proliferation of lines in my rear window despite my best efforts. They are minimized but that came at a high cost in difficulty. Even with the greater proliferation of lines that would result from a standard install in these cars, I think I would strongly urge the standard install approach and suggest that while, at first, the proliferation of lines might seem troubling - in actual practice, it might not be an issue at all. The new grid lines are maybe 1/16" wide and the lines in the glass as perhaps thinner. Humans adapt remarkably well - even to things that seem problematic at first.

That said, there is room for improvement - if only from the installation perspective. Even it the release paper were as translucent as typical kitchen waxed paper, it would have been easier for me to see what was going on. I have no suggestion as to how the grid wires could be more flexible to follow curved lines as I discovered but if not, I suggest just living with straight lines and accept the results. That said, it is difficult to orient the lines so they are plumb and parallel to the window edge unless you are able to follow a line on the window's exterior that you have placed carefully and align the release paper's edge (which you actually CAN SEE) with that line. In a standard install where there are multiple sheets of wires, the following sheets can be aligned with the bottom edge of the higher sheet. And I am sure this is what the maker intends - just NOT what I did.

It is still too soon to say if the product (as I have installed it) will accomplish its main purpose - defrosting/defogging the rear window.

Cheers

This morning, I tested continuity of all the components and connected the new grid to power/ground. As I expected (but hoped to avoid),I broke the C-Pillar trim piece (drive.google.com/file/d/12X2EvP46ai-M-b1G7fLjsLgaJXE1SrQa/view?usp=sharing") when trying to do this. Damn! I powered up the grid and I can feel it warming up. It did not feel like it was getting to 140 degrees as Jeff said they would. But it is not easy to tell. I also cannot say if it will de-mist or defog the window and that may take a while to actually see happening since things have finally warmed up here in the PNW.

My kit has arrived and I am looking it and the detailed instructions over very carefully. I can't attempt the install now it seems as the instructions require an extended period of 60+ degrees and it has been too darn cold here in the PNW. They say that patience is a virtue and mine is being tested right now.

My choice to use the 12 wire kit creates a "problem" in that they only make a compatible kit with 12 wires that has both connector tabs on the same side - whereas my car has power on the driver's and ground on the passenger's sides. I plan to place the tabs on the driver's side with power up top and that means I will have to either run a long wire from the bottom somewhere/somehow to the passenger's side OR find an alternate ground point. Not sure yet what I will do. They have a 10 wire kit with tabs on both sides. But I decided it was better to have closer to the original 13 wires. I MAY live to regret the decision.

The folks at frostfighter did let me know that shorter wires would run hotter than longer ones in my planned, trapezoidal grid layout but said the difference would not be that much. I had asked about getting a 15 wire kit and removing two so that I matched the 13 wires of the original. They were quite strong in advising against that saying doing so would make some wires MUCH more hot than others - which you don't want. So I ended up with a 12 wire kit. At that, they told me my grid should operate at about 140 degrees - which surprised me. I would have guessed more like 80 degrees. Not sure I will ever be able to tell.

I am amazed by the lines left inside the glass after scraping. It does look virtually the same from the outside as it did before scraping. But you cannot feel anything with your finger at all. I have no idea if the glass was molded with those lines in there or if some of the metal from the heated wires diffused into the glass or what. But I was warned.

I found a technical bulletin on their website that says it is ok to install wire by wire and speaks to how that is done. I have not yet decided if I will do the install wire by wire or by the sheet (3 sheets of 4 wires each). I worry that I might be bothered by the additional lines making things too busy or even impeding my view. Yet, many things I have worried about over this lifetime have proven to not be as big a deal as I thought they might be.

So here are photos of the kit's contents. Be aware that the wires (drive.google.com/file/d/1LhmHGnXzS0Ib__Rip8MO4tN-j9B96gmC/view) are a NOT part of the kit but an optional wiring harness adapter. That was about $13 and the kit was about $60 (plus shipping).

Three strips of 4 wires each (drive.google.com/file/d/13JghGjZQClwVDThq0ypcRHcmE8638Je0/view).

Pre-installation cleaner/prep (drive.google.com/file/d/1ZXbDo4BGBxgUzMWwPDyW6eOcihrKuTOo/view).

Side one (drive.google.com/file/d/18iOwbycd31n2yDrLqG5E4MJapGloPnjY/view) and side two (drive.google.com/file/d/1K21OMfLzFedzwIOqm7z6-M-E9rgJtcok/view) of the buss bars.

Compared the kits wire spacing to the original(drive.google.com/file/d/1484XBHkH7EOOt9FGOIolkSqV79Kza2pO/view?usp=sharing). Not sure I can live with this.

Their Technical Bulletin 111 - Defroster Replacement Grid Matching(16qdkyluf2-flywheel.netdna-ssl.com/wp-content/uploads/2021/01/Tech-111-Matching-Grid-Spacing-Ver3.pdf) describes doing install line by line. Glad it says "The heating element spacing is not critical".

The weather is finally warming up here in the PNW. And I have just committed myself to the line-by-line installation (drive.google.com/file/d/1O6RbbImA0aq6Rz9pQsnJR93i179DRqPc/view?usp=sharing"). As I am a total newbie at this, I fear what might happen. I also have "tested" to see if I can "see" enough of the lines in the glass through the release paper to follow them in placing the new wires. In short, the answer is NOT REALLY. So I have ordered some 1/8" blue masking tape and I will use that on the outside over the lines so I can see what I am doing more clearly. I can only hope that is enough.

Nice and warm now in the PNW for a change. Should stay this way a while. So I am plunging onward into the install.

I realized that the original lines in the glass were not going to be visible enough through the kit's release paper to allow me to follow them very well (if at all). So today I applied some 1/8 masking tape over the lines and to demarcate the center and edge lines. Here is the result from the outside (drive.google.com/file/d/1KwNp0bkyvQKkMn_PkiylrJNCcE6GQL_r/view?usp=sharing") and in (drive.google.com/file/d/136-JfREDw3VjYmYTaIZiSx4rbsb6fg1-/view?usp=sharing"). This shows the difference in visibility (drive.google.com/file/d/1BdberFcXXOvJtOMDQkAwDpOXFEDQHH0U/view?usp=sharing"). Note: I am not using this topmost line as the kit has only 12 wires compared to the original's 13.

While sitting around and re-reading the instructions (for maybe the 20th time) today, I realized that I missed the admonition on page 6 of 12 to NOT TOUCH THE BUSS BAR METAL! Well too damn late for this dummkoph! While I was working on the layout on paper, realizing that as I am not following the kit's spacing of 1.25" between lines, I was going to have to cut/modify the lengths of the buss bar metal and other components. In doing this, I made full-size drawings and handled the metal quite a bit. Not sure what I can do about that. I have emailed to find out. Damn!

Well, I just heard back from Jeff at frostfighters - he has been so tolerant and helpful. He says I should have no problems and, I can use alcohol, if there is visible contamination. So onward I go.

I don't think you have to over think the grounding issue. I don't recall if you specified if you have a sedan or wagon -- but if a sedan run the wire under the rear deck trim to the trunk and ground to the welded on hinge bracket -- if a wagon ground it anywhere on the hatch (as long a the hatch to body ground is good). -- Dave

I decided to remove the seat belt retractor covers because it would give me more room and mine are spray painted replacements that are already scratched and I don't want to scratch them even more.

I note there is a honking-big, 16mm bolt that fixes the retractor and the nut on the underside seems welded to the body metal. My volt meter shows continuity from the bolt's heat to the ground strap on the right side of my window.

Any reason to NOT use this bolt for ground? It is just below where the grid kit's ground tab will end up.

Thanks

I think this is a very poor place to make your ground. For one thing a 10 or 12mm diameter bolt (bolts are measured by the shank diameter--not the head size) is WAY overkill. Secondly, a seat belt anchor is no place to also piggyback other items. A ground only has to be -- at most -- a #10 wire. Examine the secondary ground (to body) at your battery and alternator and that will give you an idea of what's needed. Any good clean connection to a body panel/structure will accomplish what you need. -- Dave

Thanks. What I was thinking was to run a proper sized wire - I got these along with the kit - from the grid's ground tab to this bolt. I was going to solder the wire to a washer that would be placed just under this bolt's head. It is not that I am thinking it will provide a better ground than anywhere else. It is just a convenient place - rather than drilling through the rear deck and running a longer wire through the hole to reach something else in the trunk - like the hinge mounting bolt. Cheers.

Well here is the result - kind of a blend between the various suggestions. First, I had no luck whatsoever in soldering a copper wire to a large steel washer (tried to solder to a drain plug washer - which I thought was copper - and had no luck there either). No idea why but it has been suggested that I would need a larger iron than I have available. So I am basically giving up on solder joints.

One of the wires in the wire kit I purchased along with the stick-on kit came with a nice, crimped on male spade connector attached and is about 10" long - plenty to route around the plastic cover and plug into the lower tab on the grid. So I decided to sandwich that spade connector between two washers under that large bolt head on the seat belt retractor (drive.google.com/file/d/1Azkie-58sV_dockOlwHhme5hJZNB_-RE/view?usp=sharing). I again tested continuity to the original ground connection and found it solid.

fwiw

Wagon--- mine

I had to delve into the driver's side hatch harness due to No Plate lights--- a Pull-U-Over offence driving after dark.

The wiring is this Extremly Thin flexable barely twistable-looks like human hair ---did I say super-fine ... Both to the lights And the Heater Grid.

I still think you are totally overthinking this ground issue. If you are going to go through the effort of soldering a wire to a washer large enough to fit under the seatbelt mount bolt (again, a bad idea in my opinion) why not just use a normal wire loop end and attach it to sheet metal screw (or small bolt) through the rear deck? - Dave

Go for it. Your thinking is sound. It is the most convenient point and requires the least amount of effort.


--
'79 242, '84 DL 2 door, '80 DL 2 door, '89 DL Wagon, '15 XC70 T6 AWD

Thanks for the suggestion. I will consider doing that and start looking at it today (since it isn't raining).

When looking in from outside and comparing the grid wires in my car to the wife's 1980 w/replaced glass, I could clearly see a difference in mine. Spots that were discolored, varying thickness in the wire.

I had no troubles working the old grid off with the single edge blades. It is cramped and uncomfortable working in the rear seat and getting in/out in the 2-door for an old guy like me. But there is no alternative unless you remove the glass.

The window glass did NOT get scratched-up while peeling off the original grid But you have to be very detailed and go over each grid line a few times with the blade at differing angles to make sure you get it all off. Leaving anything behind but clean, clean glass is bound to mess up adherence of the new grid wire kit. I even scraped between the wires because after all these years there was a film of build up that seemed best removed this way. My final step was a good cleaning with Windex inside and out. The kit comes with some form of pre-install cleaner as well.

Be aware that even after the scraping is done, you will likely see something of a line remaining. You cannot feel it, it must be inside the glass itself. No idea what it is or why it is there. An FAQ at frostfighter.com says "The old grid will come off with a razor blade but there will be a brownish red tint in the area of the lines and that’s in the glass so it is not going anyplace." This is consistent with what I am seeing. I am a bit concerned that between these and the new grid wires there may be some reduction of "view" through the window. But I really think I am over-thinking it. We will see. There is an FAQ that speaks to installing the new grid wire by wire and that could be a solution to this. But the spacing they use for the wires is not identical to those in the car and so it is not clear this would produce results that adequately match their side bus bars and that would be a big problem. So I am likely going to plunge ahead with a "standard" install.

I also had to get access to the existing power/ground wiring. I did not want to rewire everything and to use the existing switch on my dash. The power "wires" are actually part of the tab that is glued to the window and they are not simple wires but thick, copper strips. These connect to the wiring at a connector located behind the "C" pillar covers adjacent the rear window. Ideally, I would have removed them and connect inside of there. But these plastic parts are old, brittle, and already cracked. I checked and can find no replacements for them anywhere. So I decided to leave them be, cut the copper strip as close to the tab as possible, and connect to that somehow (either soldering or some form of connector - still not sure). You can gently pull on some "slack" in the strip by slipping a small screw driver or other tool into the space where it is exposed and prying gently. I then cut through the strips using a dremel tool with abrasive disc installed. This worked well, was controlled easily enough, produced no sparks (although I was prepared for them if it had), and did what I needed done.

I now await the kit I ordered (1212-3450-L-STK). I also ordered their #2745 Tab Adapter Wire Harness. After much special checking back with their tech support I determined that this was the most optimal kit for my use in this car. Sadly, this kit has both power and ground tabs on the same side and so I will have to deal with that somehow - not exactly sure what I will do yet. To get a result that they tell me will not overload my fuse/wiring, I will cut and install the grid in a trapezoidal shape that mimics the window's shape. This will maximize the overall length of the grid wires and this will increase the resistance across the entire grid and this will lower the current flow so as to not blow the existing 16 amp fuse and wiring. At least that is their theory/conclusion. Both of these issues can be addressed using a different kit (1210-2740-STK) but it results in a smaller grid area. This may be ok but I was striving for something more optimal.

Here (drive.google.com/file/d/1Td_1BRSCSKmp4sy2dC4uhHSSPyIjWUmo/view?usp=sharing) is a photo - from the outside - of my 1983's right side defroster strip to which the tab is glued. See how pockmarked it is?

This (drive.google.com/file/d/1bDspMcDZ5tJEUlH0Je5J35XsppZHYL9n/view?usp=sharing) is a photo of the same from the wife's 1980 with replaced glass. Not perfect, but obviously far less deteriorated.

From the wife's car again, here (drive.google.com/file/d/1CVtaLhUVmb7nudWTFDEB3TgIcv5Li8JI/view?usp=sharing) is the power supply strip. Hers has more slack showing than did mine - likely from the earlier window replacement.

And here (drive.google.com/file/d/1xk9-dPgWuuwTIxb7qkfaiV3bMzaHRmGN/view?usp=sharing) is a severed strip from my 1983. You can see that some is left affixed to the tab on the window. It may be possible to knock the entire tab loose and work with that. But I feared damaging the glass in such an attempt.

From the outside, you can see here (drive.google.com/file/d/1p4ewniv6h-uzmo3V5JowPlusGEwlZ8LP/view?usp=sharing) that even once the defroster grid has been scraped off, the lines remain and are rather prominent.

And the lines can be seen from the inside as well here (drive.google.com/file/d/1dPuxqNB4VBR61vFya0ZYYoPrZxKBa5Sc/view?usp=sharing).

And here (www.youtube.com/watch?v=NnP8FCQ7JXQ) is a non-official video that helps give an idea of the install and how it all works.

Rear Window Defrost Miracle.
Easy to apply metalic impregnated paint.
Just paint over the broken or damaged grid.

EZ to apply*****

(for success, invert the vehicle for 24 hrs to ensure maximum cure.)

Hoppy All Fools Day.

Hah! You ALMOST had me there.

While I have not yet ordered, no less installed, my replacement wire grid kit from these folks, I have had quite a bit of interaction with Jeff in support questions. He has been outstanding in tolerating all my neophyte inquiries and postulated install scenarios.

I wish they simply made each kit's technical spec's and install instructions available directly for download off their web site. But you must request this information be emailed kit number by kit number. But Jeff has answered every one of my requests in a speedy fashion.

At least for my own 1983 242, the decision of which kit to buy is not an easy one. Our windows vary in width and height with the flaring of the glass. And install instructions require that you meet specific setbacks from the top/bottom and edges of the window glass. And you must be aware of the amperage that your final grid dimensions will demand. My car has the rear defroster fused on a 16 amp circuit and so I really don't want to press much beyond 14.5 amps being drawn.

They do not offer any kit that is an exact replacement for what is on my window originally. But I can come close and still fall within the install and amperage guidelines. But just barely. For my car, their kits 1212-3450-L-STK and 1210-2740-STK seems the likely suspects. The former sadly has both tabs (power and ground) located on the same side (I would put them on the driver's side) and so I would need to run the ground wire either across the rear deck and up to the existing ground strap or somewhere else - still not sure where. The latter does not pose this problem, but its height is less than what I have now. However, the smaller size may make wire grid installation in the cramped and uncomfortable rear seat a bit easier. So there are trade-offs.

One thing I would encourage is that folks first make a pattern of your window's precise shape. This makes measuring, orienting, and positioning things much easier. I have gone back to re-measure about 20 times as I have considered the strengths and constraints of various kit options. I simply taped some pieces of newspaper together, taped the result a bit loosely over the window's exterior, and used a felt pen to trace the outline of the interface between the window glass and the rubber gasket. It doesn't have to be perfect or precise. I am sure I will use this again once my kit arrives to cut the precise length and shape (either somewhat trapezoidal in the case of the first kit above or rectangular in the other case).

More later. Cheers!

I don't now if this will help you but---when I worked in a Renault/Peugeot dealership in the mid 1960's we'd track down breaks in the rear window defrosters by checking voltage along the grid. Each line would read in decreasing value the voltage from the + side moving towards the ground side. If there was no continuity you've found the break.
When I had a 544 I added a glue on rear defroster grid which actually worked pretty well -- way too long ago to remember the brand - probably "id". - Dave

Thanks Dave. I did similar using a test lamp to ground and a folded piece of foil under the test lamp point. Slid it around to see where I got light and not. All along the left side vertical strip I got light. Then started moving across each horizontal wire from left to right. On no wire did I get/keep light beyond 2". And some less than that.

When I compare my grid to the wife's 1980 (which had new/used glass put in a couple years back for this same reason) from the outside, I can see much, much more discoloration/oxidation on both the side strips and the wires. And the wires vary in thickness.

As much as I hate to do so, I have to conclude that the grid is wasted.

One other thought I had was to install something like this (www.amazon.com/gp/product/B07JZ3W5GL?pf_rd_r=QWK1DMY4JZZBPNZZC5NC&pf_rd_p=5ae2c7f8-e0c6-4f35-9071-dc3240e894a8&pd_rd_r=5b2c7ef4-edaa-4229-b7d2-f23f08dc8aba&pd_rd_w=kJdg1&pd_rd_wg=P3UpP&ref_=pd_gw_unk) on the rear deck. I could wire it to the existing wires and have it on the dash switch. But I am just not sure. None of these things seem to get decent reviews.

This stuff is interesting:

https://www.amazon.com/Permatex-09117-Complete-Window-Defogger/dp/B000ALBZJY/ref=asc_df_B000ALBZJY/?tag=bingshoppinga-20&linkCode=df0&hvadid=&hvpos=&hvnetw=o&hvrand=&hvpone=&hvptwo=&hvqmt=e&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=&hvtargid=pla-4583932699345293&psc=1

It is. But it turns out that my existing grid wires are NOT broken - just corroded and oxidized to hell. It seems this sort of thing is for repairing a break or cut in a wire and I assume it will do that well enough. But I think that mine is just too far gone and more drastic measures are required. Cheers

As I have decided there is little option but to try a stick-on kit from frostfighter.com, I have started the process of prep. The first step is to remove the existing defroster grid wires from the glass so there they are not there to affect the attachment of the new grid wires from the kit. As such, I have taken a single edge razor blade to a couple of the grid wires.

The results of doing this says ALOT about the condition of those grid wires. What comes off varies quite a bit! In some places you get something akin to a spiral of thin tape coming off the glass. And this is what I would expect. But in many other places, all that comes off is a powder - more like dust. It just flakes off and has little substance and no coherence at all. This happens in various places across the window's width and height. I see no real pattern. And just looking at it does not make the distinction between the two obvious at all.

I think this speaks volumes about what has happened here. Over time, what was once a thin, metal strip has decomposed into line of often-rotten, oxidized garbage that is unable to conduct power any longer. This seems far beyond something like a paint-on patch.

Once I get this off and the window surface really clean - not easy in itself given all the years of neglect back there - I will try to cut the power and ground wires close to the tabs that are glued to the window. The wires do not just clip onto the tabs as I have seen on many other cars. They are actually part of the tabs and run to a connection under the "C" pillar covers. I am not interested in touching those covers as the plastic is old, brittle, and already cracking. Plus, I have looked all over and cannot find replacements should I bust one. Once cut, I will then solder or clip some properly-sized wires to extend the reach to accommodate the kit's connections.

Once this is all done, I will place an order for the kit itself. Choosing the right one isn't quite as easy as one might think. The size of the grid directly impacts the resistance and current flow. And the existing defroster wire circuit in wired/fused for 16 amps. So you don't want to exceed that otherwise blown fuses will be the result every time the defroster is engaged.

It seems that the resistance in the kit wires is different (higher) than the original wires. My grid has 13 wires spaced about 3 cm on center. And they run the entire width of the glass. A 12-wire kit is the closest they offer but it is spec'ed for a 25 amp circuit. So some compromises must be made and care must be taken in the selection.

Cheers