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Repairing Your Rear Window Defroster

It snowed last night. I mean it REALLY snowed last night...

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» Doesn't Work At All
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Doesn't Work At All

Let's say the rear window defroster doesn't work at all. If you have been hanging around here any length of time you know the first thing to check is the fuse. Rear window defrosters draw a ton of current so if you have a fuse that's too low, it won't last long. If the fuse looks good, check it with a test light or voltmeter. You should have battery voltage on both sides.

If the fuse and voltage tests are both good, the problem is in the wiring or in the defroster grid itself. Look at the sides of the grid. There is a terminal on each side and sometimes they fall or get knocked off. If one or both have come of and are just hanging there are two ways to repair them. You can glue them back on or you can solder them back on.

If you know how to solder and have a 200-watt soldering gun or iron, you can solder the terminals back on to the defroster grid. A third hand is very handy in doing this so get the spouse to come out and help you for a while.

Most times there is a metal backing strip below the silk screening and attached to the glass. Clean the area well, alcohol works best, and use 60-40 rosin core solder. DO NOT USE ACID CORE SOLDER!! It will eat away all the metal parts over time and leave you with nothing. Make sure your soldering gun or iron is hot before you solder the terminals. Work as quickly as you can to keep the glass from getting too hot and possibly cracking.

If you don't think you have the soldering skills necessary or are just afraid of cracking a very expensive window, there is an alternative. Some dealers and larger auto parts stores sell a special electrically conductive epoxy to glue the defroster terminals back on. If it's cold out, you'll need to work in a garage that is heated and the whole car warmed up to above 65° F.

To do this with the epoxy you need to clean the area, again, alcohol works best. Using tape, mask off the area so you don't get epoxy where you don't want it. Read the package directions and mix up a small amount of the hardener and epoxy. You don't need a lot for this. Now put a little epoxy on the defroster grid and a little on the bottom of the terminal. Place it in position and use a toothpick to hold it in place until the epoxy sets up. This usually takes about 10 or 15 minutes or so. You can dampen the end of your finger with water and move the epoxy around to make it look better if you want. If you do this you have to do it in the first minute or two or forget it.

After the epoxy has set up, don't even think about connecting the wire to it. You did disconnect the wire, didn't you? It takes about 24 hours at above 65° for the epoxy to cure to its full strength. Now this repair will not be as strong as the original so be very careful putting the wire back on and be extra careful when you clean the inside rear window.

» Part 1       » Part 2       » Part 3       » Part 4
Additional Information provided courtesy of and Warranty Direct
© 2000-2007 Vincent T. Ciulla

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