03 4.0l rear defrost only half works

[Scurvy]

My 2003 expo is being finicky with the rear defrost, only 4 lines on the back window are defrosting, two on the middle and two at the bottom.

I've read some other threads about the entire rear defrost system not working but those all seen to be an all-or-nothing situation whereas I'm still getting SOME function from the rear defrost, just not the whole window.

Considering my symptoms what is my most likely culprit and how do I check that component?

Thanks!

 

[mountaineer2004]

The individual lines are broken. Age or they got scratched. Happened to me too.
Go to auto store and get the grid line fix, it's some gooey mix that fixes it. Good luck.

 

[Scurvy]

The individual lines are broken. Age or they got scratched. Happened to me too.
Go to auto store and get the grid line fix, it's some gooey mix that fixes it. Good luck.

OK so then theoretically I should be able to see where they're damaged to confirm that's the issue? Should I be looking at the inside or outside of the window? And that grid line fix stuff should be available at most parts stores?

 

[mountaineer2004]

^^^ Yes. Inside of window. If you look closely you should be able to see where the element is broken.
If you don't see the damaged section, look again, it's there somewhere. Most, if not all, car stores carry the grid line repair kit.

 

[Scurvy]

OK thanks. I did some googling and found how to test the grid lines with a test light. I'll report back when I've done some work on it and let y'all know how it works out.

 

[bhieb]

OK thanks. I did some googling and found how to test the grid lines with a test light. I'll report back when I've done some work on it and let y'all know how it works out.

Hi,
I have the same problem where only part of the rear window defrost works. I'm curious to learn about how you tested the grid lines to find out which ones were open circuited and how you fixed the ones you found that were bad.
Brad

 

[Scurvy]

Hi,
I have the same problem where only part of the rear window defrost works. I'm curious to learn about how you tested the grid lines to find out which ones were open circuited and how you fixed the ones you found that were bad.
Brad

I haven't dealt with it yet (been too busy with other stuff) but if you search youtube you'll find your answer for how to test and fix it.