Step 2: Problem: No Heat At All

Suppose your defroster grid doesn’t work at all. First, check the obvious: Is the fuse okay? Defroster grids draw a lot of current (10 to 20 amps), and if the fuse is undersize, it won’t last. If the fuse doesn’t look blown, check with your voltmeter—with the key on and the defroster on, you should see 12 volts at both fuse terminals.

If the voltage is fine, the problem is somewhere in the wiring or at the grid. Check the connections from the wiring harness to the grid. It’s easy for the terminals at the grid to become damaged. Generally, the tab that’s attached to the glass breaks off, leaving you with a dangling wire and no way to reattach it. You have two repair options here: soldering and gluing.

If you know how to solder and have a high-capacity soldering iron or gun, solder the tab back on. It may take a third hand to hold the tab against the grid while you solder it. There’s usually a metal strip laid on the glass under the silk-screening. Clean the surfaces with alcohol and use 60-40 rosin-core solder. Work fast, because excess heat may crack the glass.

If you aren’t confident about your soldering skills, or aren’t ready to take a chance on cracking an expensive piece of glass, there’s another way. The dealership and most auto parts stores can sell you a special electrically conductive epoxy to bond the tab back on. If it’s wintertime, you’ll need to work in a heated garage, and have the vehicle inside long enough for it to warm up to at least 65˚ F.

Again, clean the area with alcohol. Mask the glass with tape to keep from getting epoxy smeared on it. Mix up a sparing amount of epoxy and hardener. Put some epoxy on the tab, and use an ice pick to hold it in place for the 10 minutes or so it will take for the epoxy to harden. You can use a wooden stick or the end of your dampened finger to smear the epoxy within a minute or two of application to improve the cosmetics of the repair. Although the epoxy will set up rapidly, don’t attempt to reattach the wiring until it’s had 24 hours at 65˚ F or more to cure and achieve its full strength. The repair will never be as strong as the original wire, so you’ll need to be particularly careful not to damage it in the future.
<p><a href="http://www.amazon.com/gp/product/B003BDMJSY/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B003BDMJSY&linkCode=as2&tag=goodkcom-20&linkId=VJKHDFHGVARSG36S" rel="nofollow">MG Chemicals 8331 Two-Part Silver Conductive Epoxy will do the trick!</a></p><p>1 - Remove drivers side rear glass panel by using a panel popper.</p><p>2 - Remove tab from wire.</p><p>3 - Remove <br> solder on bottom side of tab that will attach to window. I initially <br>tried to use a solder gun but found using a drill gun with a wire brush <br>attached 'sanded' the excess off with ease.</p><p>4 - Clean tab and location on glass with rubbing alcohol. Make sure the new location is not the same one where the tab fell off.</p><p>5 - Use <br> a small vice grip to hold the tab. I found a great location where I was <br> able to use the back seat top cushion to jam the vice grip to help hold <br> the tab to the glass window. It was very sturdy.</p><p>6 - Grab a piece of <br>cardboard and a stir stick. Squeeze out epoxies at a 1 to 1 ratio(1 black <br> tube 1 white tube), I only ended up using maybe 1/4 of the tube. Stir <br>very well. It will take a while for the epoxy to harden, so no need to <br>rush.</p><p>7 - Use stir stick to generously apply the mix to the tab. (I put a <br> small amount on the bottom) Make sure you spread it around to contact <br>the circuit on the glass.</p><p>8 - Use a hair dryer to help harden the epoxy. <br> Very important: Don't mess with it while it is drying! I propped up a <br>hair dryer and set it to low heat since it was only about 6 inches away <br>from the tab. Left it on for 20 min. Came back and the epoxy had <br>hardened.</p><p>9 - Remove vice grip and reattach wire to tab</p><p>10 - Test with multimeter before reattaching panel.</p><p></p>
<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>

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