Defrost wires - intermittent repair behavior

[07Blazerman]

Ok so a few months back, the bottom 3 lines on my rear defroster stopped working, I found the breaks in the lines and purchased a repair kit at O'reillys Auto and repaired them. All 3 lines were working again, then one by one they stopped working. Checked them and saw the repairs chipped off-and window was never touched so I decided to order the frostfighter.com kit thinking this was better. Cleaned off the old repair and cleaned the window with glass cleaner and then alcohol making sure it was absolutely clean. The first time I only cleaned with glass cleaner per the first kits instuctions. Made the second repairs and all but the bottom were working again. I checked it and no breaks, so I couldn't figure out why it wasn't working. After a few days it started working but the 3rd one up stopped working, then the next day it started working but the 2nd one from the bottom stopped working. Now this morning on my way to the gym the 2nd and 3rd were not working but on the way home they were working and the bottom stopped working. They alternate between working and not working without being touched and have done it numerous times over the last 3-4 weeks. The fuse is good and was replaced a few months back, the 2 connectors are nice and tight and look to be in good shape, so anyone any ideas because I can't figure it out and I am about ready to have the glass replaced at the dealer for $700 when I get my bonus, but I would rather spend it on new shocks. Thanks, Paul L

 

[Blckshdw]

It's gotta be something local to the repairs you did. Somehow they are losing contact, and current isn't flowing through them 100% of the time. I haven't had to use one of these kits myself, maybe you need to have a little more overlap from the repair material onto the existing lines? Just throwing out a guess.

 

[The_Roadie]

I also recommend more overlap and cleaning to expose bare copper. The wires and the patch get hot when in use, and any slight difference in the thermal expansion of the patch compound compared to the glass-mounted printed circuit wires is going to open up microscopic cracks.

 

[07Blazerman]

I also recommend more overlap and cleaning to expose bare copper. The wires and the patch get hot when in use, and any slight difference in the thermal expansion of the patch compound compared to the glass-mounted printed circuit wires is going to open up microscopic cracks.

After further inspection the repairs just flaked right off, I cleaned it really well again and just decided to just cover the whole area and took your advice and went beyond and wider on the repairs . We will see if this works, I just wonder if temperature has anything to do with it. I did not see any warnings on either package for a minimum temp. Thanks again.

 

[The_Roadie]

APPLICATION temperature is almost always specified, and I can't imagine epoxy curing up in too low a temp. OPERATING temperature should be suitable to the application, and defrost wires are one of the most extreme temp extremes in the body. You only tend to use them when it's wicked cold.