The rear defrost wires kept falling off of the window. i had them soldered back on several times until i finally had to replace the entire glass, because there wasn't enough material to be able to re-solder it. within a couple of weeks of replacing the glass, one of the wires fell off. i had it fixed. then a few weeks later the other one fell off. in total over the next year i had both wires re-soldered at least twice each, until just last week when i had to replace the glass again! i was told that this is a bad design by gm and that they tend to fall off because they get too hot when in use. however, the wires even fell off in the spring and summer when the defrost wasn't in use. *tr