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Discussion Starter · #1 ·
Does anyone know what the DC resistance of the rear window defroster is on the GT? I went to a junk yard today and purchased what looks to be a stock rear window with the defroster and tinted but it doesn't work, Shame because the shape of the glass was amazing.

Is there any company out there reproducing the rear window glass with the rear defroster? I am sorry if this post is in the wrong section; however, I searched the site for a windows section, but only saw window trim section.
 

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Über Genius
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I don't know the resistance but if you took a meter and checked continuity, you would be able to determine if the elements are toast.
ANY continuity would cause the defroster to work (even in part). If you have zero functionality then you either have a blown heating element or a bad circuit.

Something to consider. The more elements that fry, the easier it is for others to fry. That's why it's important to always repair the elements if they fail.
 

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Sometimes you can use an ohm meter to determine where the grid is broken by carefully using the probes to look for a break in continuity. A change in resistance will indicate that the current is having to go around the break via one of the other grid circuits. If it goes "open circuit" then there are at least two breaks: one behind the outer probe, and another one behind that break!

There used to be a product sold that was a conductive paint specifically for repairing rear window defrost grids. You might check with an automotive supply store. An alternative is called a "conductive pen" which leaves a thin trace of silver, almost like a roller tip ink pen but the "ink" is actually conductive, and made of a solution that leaves a trace of actual silver. Some are actually "solder-able" but only at quite a low temperature. That and/or copper circuit tape can work to repair cracks and scratches in the grid. Both are available from an electronics supply store.

There are aftermarket stick-on grid defrosters that work fairly well. I have used them a couple of times, and I have a kit ready for when I install my rear window. It can be tricky to install them when the window is already in place as there isn't much room back there to work.

HTH
 

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I'm sure it can be purchased in other places, but Ford sells the silver conductive paint made specifically for repairing the window traces. I've used it many times and it's always worked perfectly.
 

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I spent hours yesterday trying to find the open or opens but was not very successful. I did reattach the two electrical tabs as they were off when I found them. I carefully cleaned the contact points with rubbing alcohol and #0000 steel wool prior. I also wire wheeled the terminal to clean years or oxidation from it. Before attaching I tried to measure the resistance and it was open or at least greater than 20 Meg Ohms, Meter's capability. The meter and leads are working properly.

The window from my car and the junk window both measure open.

I am disappointed because I am the type of person that if it is installed on the car it has to work. I am trying to make this a show car but not an all original one. Just has to look stock but will have subtle mods for modern safety and performance. For example three point replacement seat belts, larger brake booster and master cylinder, lower stance by 1 inch, Weber carb and header.

What would most of you guys do? Install the real nice non-working factory tinted rear window, install the one that came out that doesn't work and is clear glass with terrible deep scratches, try to find another used one that works or find an after market one that works. I guess I could also try to take it to a glass place to see if they could repair it.
:confused:
 

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Über Genius
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I spent hours yesterday trying to find the open or opens but was not very successful. I did reattach the two electrical tabs as they were off when I found them. I carefully cleaned the contact points with rubbing alcohol and #0000 steel wool prior. I also wire wheeled the terminal to clean years or oxidation from it. Before attaching I tried to measure the resistance and it was open or at least greater than 20 Meg Ohms, Meter's capability. The meter and leads are working properly.

The window from my car and the junk window both measure open.

I am disappointed because I am the type of person that if it is installed on the car it has to work. I am trying to make this a show car but not an all original one. Just has to look stock but will have subtle mods for modern safety and performance. For example three point replacement seat belts, larger brake booster and master cylinder, lower stance by 1 inch, Weber carb and header.

What would most of you guys do? Install the real nice non-working factory tinted rear window, install the one that came out that doesn't work and is clear glass with terrible deep scratches, try to find another used one that works or find an after market one that works. I guess I could also try to take it to a glass place to see if they could repair it.
:confused:
^this
 

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The tiny defroster conducting elements within the glass are vulnerable to corrosion from the combination of direct sun exposure and internal car moisture. The metal conducting strips were not located to be accessible where they run within the glass for service, and their metallic formulation was not designed to last for 40 years.

Replacements were sold in Germany in the 1990's in various tinted shades, and there may still be a pane or two available from someone's old stock if you track it down.
 

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Kalifornia Kid
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Purchased a universal rear defroster grid kit from JC Whitney back in the mid 90s for my Kadett. It was a very nice kit that was very easy to install with the glass out of the car. Came with the timer electronics with an automatic off feature, relay etc.
The only draw back was the grids were about double the thickness of the oem ones. With the Internet search engines today, I can only imagine you'd find a nice kit that features skinny grids.
 

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I did reattach the two electrical tabs as they were off when I found them. I carefully cleaned the contact points with rubbing alcohol and #0000 steel wool prior. I also wire wheeled the terminal to clean years or oxidation from it.
What did you use to re-attach the electrical tabs to the glass? I'm in the same spot and would liket to attach them back on the window.
 

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Would like to inform anyone looking to REPLACE the worn off grids on their rear window on an Opel GT that there is a replacement grid only, or complete system available. I am replacing just the grid and side bars as my 73 GT has a defroster already installed. The existing grid however is almost completely gone. Part number 1210-2740-STK from Frost Fighter & Clear View, replaces all the grid lines and the two side bars. Cost is less than $50.00 at the time of this posting plus shipping. I removed the rear window to install this, used steel wool and glass cleaner to remove all but the resin (thin lines) on the glass. Follow the directions on the kit, make sure you have power going to the wires in back, (often the ground wire is not making contact, it is located with the rear lights and grounded to the body. Also check the ground on the relay by the fuse panel to make sure the relay is activating and sending power to the rear window. They also have complete kits for windows that do not have existing wires going back there. This includes the relay, switch and fuse link. The kit above is strictly to replace the grid lines and side bars. Hopes this helps someone. There are several size kits available, you can add more or less grid lines by picking the different kits. The kit listed above matches what was in the car from the factory. The bars are thicker than the OE painted on bars so you MUST allow clearance on the sides for the window seal, Other than that, easy peasy install. Install will be almost impossible with window in place unless you are a rubber band.
 
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