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DIY: Repairing Your Rear Window Defroster

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DIY: Repairing Your Rear Window Defroster

   It snowed last night. I mean it SNOWED. Your car is buried under seven inches of snow. You open the door, start the engine and turn on the rear window defroster. It takes a little while to clear the snow off your car and by that time the engine has warmed up enough to clear the windshield and started to clear the side windows. You look at the rear window and see that there are only a couple of clear strips and the rest of the window is still clouded over and impossible to see through.

   Fixing small breaks in a defroster grid is fairly easy to do. You can go to NAPA, Auto Zone or any of the big auto parts store and get a rear window defroster repair kit. The alternative: climb in the back seat and scrape the rear window with your small window scraper. And that is not really a good idea.

   Warning!

   The defroster grid is silk-screened on, literally painted on to the glass. If you ever painted window trim you know it doesn't take much to scrape paint off glass. The defroster grid is easy to damage and the grids that are scratched will not work because continuity is broken. Any hard object such as furniture, boxes and toys can scratch the defroster grid. A simple credit card is enough to damage the grid. This can be prevented by not jamming stuff into your SUV or van and having it shift into the rear window. The only thing that should touch the window glass and defroster grid is a soft cloth and some glass cleaner. If you must scrub, do it gently and in the direction of the grid, not across it.

   Replacing the rear window to repair a defroster gird is the last thing you want to do. A curved style of rear window on most cars can be several hundred dollars and for a SUV or mini-van, over $1000.00. Include installation and it's a lot more. Don't bother to submit the bill to your insurance company either; they'll just say, "Sorry, window glass is not covered."

   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.

   Copyright © 2000 - 2003 Vincent T. Ciulla All Rights Reserved

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