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The past couple of mornings it has been in the low 30s overnight here in GA and my E350 will not defrost the rear window - at least not in the way I'm used to seeing. I can't say for sure if it ever did work correctly, just that I've now noticed it. A very light layer of frost took 29 minutes to mostly disappear, requiring it to run for 2 full cycles and part of a 3rd. But none of the lines on the rear window ever became visible like I'm used to seeing. More it defrosted slowly from around the edges inward, which makes me think it was likely do to cabin temp. Touching the rear glass after 29 continuous minutes of use and it was still ice cold but I'm not sure if I should feel that or not.
The car has had the rear window tinted, then removed, then tinted again due to tint shop error. This was months ago so I have no idea if I have any recourse there.
Is this something that would show up during a scan? Are the fuse locations in the same place they were for the 2010s?
Close inspection shows no visible damage to any of the wires along the rear glass. But the pattern that you refer to and that I'm used to seeing in every car I've ever had - nope, does not appear in this one. It simply slowly defrosts from the outside edges inward.
Thing is, I can't remember ever noticing this before so who knows if it has always been that way. I doubt I bother fixing this if it will require replacement of the window.
I had to get the rear hatch window replaced on my wagon because the heating element had failed and it's part of the window. The bronze lines were practically gone, barely visible.
Close inspection shows no visible damage to any of the wires along the rear glass. But the pattern that you refer to and that I'm used to seeing in every car I've ever had - nope, does not appear in this one. It simply slowly defrosts from the outside edges inward.
Thing is, I can't remember ever noticing this before so who knows if it has always been that way. I doubt I bother fixing this if it will require replacement of the window.
I believe it is not working correctly, Mine both clear the glass, lines first very quickly in the first cycle. After running awhile do all the lines show up as distincly defrosting? Sometimes even the slightest razor mark can reduce current flow. Hard to find.Maybe one of the wiring connectors is not making great contact after the two tint applications?
Last edited by pierrejoliat; Apr 4, 2021 at 09:28 AM.
The past couple of mornings it has been in the low 30s overnight here in GA and my E350 will not defrost the rear window - at least not in the way I'm used to seeing. I can't say for sure if it ever did work correctly, just that I've now noticed it. A very light layer of frost took 29 minutes to mostly disappear, requiring it to run for 2 full cycles and part of a 3rd. But none of the lines on the rear window ever became visible like I'm used to seeing. More it defrosted slowly from around the edges inward, which makes me think it was likely do to cabin temp. Touching the rear glass after 29 continuous minutes of use and it was still ice cold but I'm not sure if I should feel that or not.
The car has had the rear window tinted, then removed, then tinted again due to tint shop error. This was months ago so I have no idea if I have any recourse there.
Is this something that would show up during a scan? Are the fuse locations in the same place they were for the 2010s?
Reads to me that it is not working at all. You should see the lines visible if working... clearing from the edges is just cabin temp defrosting as you've observed.
I've had rear window tinting on every car I've owned since 1985. Rear window tinting covering the defroster grid plays no role in it at all, unless a tint installer cut one of the leads, or pulled the grid loose in removing the tint...
I believe it is not working correctly, Mine both clear the glass, lines first very quickly in the first cycle. After running awhile do all the lines show up as distincly defrosting? Sometimes even the slightest razor mark can reduce current flow. Hard to find.Maybe one of the wiring connectors is not making great contact after the two tint applications?
Maybe. I can't find any damage, but the lines never show up in the frost. I ran it once until it timed out, ran it a second time till it timed out, ran it part of a third time. Never got the distinct lines that you're referring to. Actually not even slightly. I do not believe it to be working at all.
I've had rear window tinting on every car I've owned since 1985. Rear window tinting covering the defroster grid plays no role in it at all, unless a tint installer cut one of the leads, or pulled the grid loose in removing the tint...
Same, I always have tints and have never had an issue.. but this time, the tint shop installed the incorrect tint and had to redo it.
Maybe. I can't find any damage, but the lines never show up in the frost. I ran it once until it timed out, ran it a second time till it timed out, ran it part of a third time. Never got the distinct lines that you're referring to. Actually not even slightly. I do not believe it to be working at all.
I might start with the connections for power, I believe they use water or washer fluid to install the tint, having been done twice and removed once, there might be a chance that the connectors got corroded slightly.
There is no visible damage at all on my car. I went over the rear window and I don't see so much as a scratch on any of the wires/lines.
Guess I'll have to have this diagnosed, and then I'll go to the tint shop.
I still wonder if one of the wire connections is corroded. I do not mean in the glass but in the trunk at the wiring harness connections, I also did not mean to indicate that the tinting itself was involved at all, just that the installation and removal may have used enough liquid to corrode the connections to the wiring harness.
Last edited by pierrejoliat; Apr 4, 2021 at 01:29 PM.
If you can access one of the leads to the defroster and put an amp clamp over it... should be pretty obvious if its drawing power. Another option, depending on the fuse layout is to perform a voltage drop test across the fuse in question with defrost on and off. On older chassis it was usually a separate ~25A circuit... so quite a bit. I've never felt a defroster actually generate enough heat to "feel" warm to the touch.
2016 E350 4Matic wagon, 2019 Ford Expedition, 2019 Chevy Bolt EV
i've fixed a few rear window defroster grids on older cars when a few lines were broken via a kit youi can buy at a local auto part store. the kit is basically a tiny bottle of conductive silver paint, and some special masking tape, and another paint to put over the first once it dries. you need to carefully inspect the broken wire and find where its broken, then very carefully sand off the insulation paint for about 1/4" in each side, lay down the masking tape, paint the silver paint, let it dry, then paint hte insulation paint and remove the mask. repeat this for each broken 'wire'.
but if the whole grid is damaged by removing old tint, or whatever, its probably too much to fix this way. I fixed 4 'wires' on an old Volvo wagon this way, I wouldn't want to have to fix 20+ spots.. In the case of my old wagon, a new rear window was NLA, so its the junkyard for another one, or fix what you have.
Things to check: f49 (40A), C relay, and connections @ trunk fuse panel. Could be relay however, on occasion wiring, connector (check all connections), and pins may melt due to corrosion and sometimes amperage. Here are photos of window connections should you decide to inspect.
Last edited by konigstiger; Apr 4, 2021 at 03:39 PM.
Relay is good, fuse is good, voltage drop does happen. Rear defrost does not function.
Not good enough to disassemble anything further. I will ask dealer to evaluate @ 50K service but if not covered under CPO, not sure I'll repair it at all.
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