from Goss’ Garage by Pat Goss

On frosty mornings drivers turn on their rear defoggers expecting comforting, visibility improving, widening lines of clear glass as the frost melts off the rear window. But for some the frost remains stubbornly in place dangerously blocking rear visibility. Unfortunately the need to get to work trumps good sense so it’s press on regardless.

If there can be a positive to a problem in this case it’s that the cause is often nothing more than a disconnected rear defogger wire-connector. It’s more common than you might think, especially on SUVs and Mini Vans as both are frequently used to haul oversized, unwieldy stuff that doesn’t always quite fit behind the rear seat. But drivers are very resourceful and they force-fit the package to the space with a strategically placed butt-thump on the tailgate! Sit outside a big box store or home center and you’ll see it.

However, forcing six cubic feet of package into three cubic feet of space may have consequences! Your butt-thump closed and latched the door but it also squeezed your package against one of the rear window defogger wire-connectors. Problem is those connectors are only glued to the glass and are easily knocked off. A loose connector means no path for the electricity that heats the glass so you and your window stay frosted.

Fortunately, it doesn’t take an automotive genius to recognize that a dangling wire at the rear window probably relates to the non-working defogger. But although you can plainly see the broken piece, you can see where it was attached, and that it was originally glued in place if you’re like most do-it-yourselfers you’ll screw up a really simple fix. Re-gluing the broken part is an easy job but most do-it-yourselfers use the wrong adhesive and cause a worse problem. Here the glue has to do more than bond two parts together but you don’t know this and through oversimplification pull off a costly blunder.

Like most over-skilled but under informed handy-people you shop for your glue-of-choice in the glue aisle at a home center. Home centers have specialty glues that bond just about anything imaginable. Wood, plastic, leather, ceramic, glass, metal, you name it they have a glue for it. So wanting a permanent fix you select a miracle product that claims, “One drop will bond a Wildebeest to the bottom of a bridge for 100 years.” Perhaps true but really, do you own a Wildebeest and a bridge? I thought not, plus I can envision a couple of logistical problems with this and most other miracle product claims. Miracle glues may be great for some jobs but they do not work for reattaching defogger terminals to rear window glass. Then you’ll probably convert a small mistake into a big mistake with a little extra glue for a super-strong fix. Yep when your super-strength glue cures it is strong enough to hold a Wildebeest to a bridge. Am I great or what?

But the next frosty morning your defogger won’t even defrost one line on the glass. You recheck your repair and it looks great so now what? You don’t have test equipment and if you did you don’t know a latching relay from used bubble gum so it’s time for professional help. Okay the used bubble gum is easy but the relay?

The guy at the shop works hard to keep from laughing as he explains that fixing your gluing fiasco will cost you an extra $150.00. That’s because that super-duper sticky-stuff you used has to be removed which will take a couple hours and has to be done very carefully to avoid shattering a break-the-bank expensive window.

What went wrong? Normal adhesives do not allow electricity to pass through them while the proper glue does. Defogger repair glue bonds the metal tab to the glass and it also conducts electricity from the wire through the glue and into the glass. Defogger repair glue is available from auto parts stores in inexpensive kits. It also just happens to be a really easy do-it-yourself or professional fix if … you know … what you’re doing.