johndeerebones

I was wondering if any of you have rear defroster problems or if it is a known problem.

My problem is that part of my window doesn't defrost. Not a problem now, just the morning dew on the windows, but it will suck with the snow and ice this winter. The top 6 inches or so and the bottom 6 inches or so don't defrost. The middle does. I have went over the side I can see from outside and the side I can see from the inside and can't see any grid damage that would cause this. Any pecuilar thing to look for or any ideas?

lazlong

It either works or it doesn't. Get some conductive paint at the auto parts store and paint the whole line(s).

CraigW

iTrader: (1)

The top area section is antenna, the bottom sounds like some damaged grids possibly.

johndeerebones

I thought of doing that. I can't see any bad spots in it. I have some high content silver epoxy from frostfighter from having to reglue the contact on my Yukon's back glass. It doesn't have a brush and is a little thick though, would have to get something else.

Craig: I know that, just can't see any break in it at all, went through it with the strong eye to try to find something. They would have to use the same circuit, which means the defroster grid should still go all the way up too. I know they run on the same circuit, the radio reception is terrible when using the defroster.

CraigW

iTrader: (1)

How many grids are inop at the bottom ??

Have you looked for the breaks with a magnifier ??

IIRC if there is an open it creates noise in the radio, and it's a crappy excuse for an antenna to start with.

If you apply the patch liquid keep it thin and only apply it a the open spot.

johndeerebones

It is like 3 or 4 at the bottom. Really payed attention to it this morning. The drivers side is inop, the passenger side works. Obviously it has a break somewhere. I haven't went at it with a magnifier. That makes sense that a break would make noise in the radio. Never though of it. My wife's yukon does that too though so hadn't put two and two together. Agreed its sucky for an antenna. I will look with a magnifier and maybe get some patch....

GolNat

iTrader: (7)

If you have an ohm meter you can ohm out between the traces to see where the break is.

lazlong

Wow, very astute. I completely forgot about that. +1

@ johndeerebones: Make sure the circuit is off. You can't ohm out a live circuit.

johndeerebones

Ya, I know. I am actually pretty good with electrical after all my schooling and turning wrenches since I was old enough too. I have spent no more time on it than it took me to look it over good. I haven't even tried to ohm it though. I thought there was some film or something over the traces to be honest. Maybe not though....

GolNat

iTrader: (7)

There is a film but you can still measure through it. If you wrap a piece of aluminum foil around the tip of the probe and use your finger to hold it against the trace you will get a good reading. Also if you turn the ignition on and the rear defroster switch on and connect your negative to ground you should read 5 or 6 volts to the center of each element if the element is unbroken. If the element is broken then the voltage will be 10 or 12 volts and the break is between the center and the ground side. If there is no voltage then the element is broken between the center and the positive side.

johndeerebones

Thanks for the info all! I was a mechanic for a lot of years before I am now a full time student, so tools are not a problem at all!

johndeerebones

I had some time to probe it tonight. It was obvious. My meter leads are Blue-Points from the Snap-On man. They are extremely sharp, the aluminum foil trick wasn't needed, BUT there is some kind of protective film over them on the inside. The bottom two grids are working, did find where the antenna stops and the grid begins. The upper portion is fine. The bottom two grids work, then three don't, then the rest do. This is only the three on the driver's side, the passenger side ones work. Anyway did find with a pen light that those three grids have most like had a decal or something scraped off them and they are a little scraped up. Don't know, I am not the first owner of the car. Anyway. Found a permatex kit for grid repair, so when I get to it I will try it out and letyou know how it works. The kit is a mask kit and touch up paint type of paint brush.