It was a dark and stormy night. Snow has covered the entire car to a depth of several inches. It takes a few minutes to clear the snow, and by then the engine has warmed up enough to melt the frost clinging to the inside of the windshield, and has actually made inroads to the frost on the side windows. But the rear-window defroster clears only a narrow strip near the top and bottom  the window, leaving a wide strip of glass as translucent as a barrister’s door, and absolutely no visibility to the rear.

A worse scerio: The rear-window defroster grid has packed it in completely, requiring you to either drive blind (bad idea), or resort to scraping the rear window clear with your trusty wooden-handled snow scraper (really bad idea).

Now what?  This Instructable will help you identify and repair some of the most common rear-window defroster problems, as well as tell you how to avoid further damage to your defroster.  Try these repairs yourself, and save money and be safe this winter!  

This project was originally published in the January 2001 issue of Popular Mechanics.  You can find more great projects at Popular Mechanics DIY Central.

Step 1: How to Damage a Defroster


Let us make this perfectly clear: Do not try to scrape hard frost from a rear window equipped with a heater grid. The resistance wires are silk-screened, essentially painted, onto the glass. They are very easy to scratch, and will not work properly if the scratch breaks the continuity along the wire. This means that it’s possible for boxes, furniture or any other hard object one might place in a car to scratch the wire. Even a credit card can damage it. Don’t cram stuff into the back, and don’t let the load shift backward in your miinivan so that it touches the glass. If your window has a defroster grid, the only thing that should ever touch the glass is a soft cloth dampened with window cleaner. If you must clean the rear glass, scrub gently, and in the direction of the grid, not across it.

You don’t want to have to replace the glass to effect this repair. The compound-curve style of rear window is several hundred dollars, and a large hatchback’s backlite on, say, a Camaro, can easily top a grand or more. Add to this installation att the dealership or a glass shop—it’s definitely not covered by insurance.
<p>LOL but how to repair ?</p>
<p>great info, i hope i never need to repair mine.</p>
<p>This 'ible is really about how to find the problem with a rear window defroster, not how to repair it.</p>

About This Instructable



Bio: The official instructable for Popular Mechanics magazine, reporting on the DIY world since 1902.
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