Rear Defroster repairKAOS said:
If it was just a scratched defroster line, you can buy repair kits which are essentially paint with lots of metal particles in it. However, I haven't heard of any way to fix a broken connector. I hate to say it, but how much is a new rear window?
Blower motor resistor
It sounds like the blower motor resistor has a couple of burnt out connections. The resister is on the front-top of the blower motor unit. You can get at it by removing your glovebox. If you pull it out, you'll see that it's got a few coils of wire that act as resistors (for each fan speed setting)...if these coils are broken or corroded, the corresponding setting on your fan switch won't work. Replacement is the best way to fix the problem. (or, if you are electronically inclined, I'm sure you could figure out a way to wire in some big replacement resistors...if you knew the original resistance settings.