The rear window defogger in my 2001 Chevy Malibu doesn't work. When I press the button to turn it on, the light in the switch goes on indicating that everything is working but it's clealy not working. I'm not sure if this is a problem with the fuse or what. Everything else electrical works fine with the vehicle. Any advice would be greatly apprecaited.

Carefully remove the connector and clean the contacts with 240-grit abrasive cloth. Afterwards, it would be a good idea to apply a light coat of dielectric grease to the contacts. If the problem persists, check all underhood and underdash fuses with a test light or multimeter:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post252145

If the grid isn't getting hot at all, follow txgreasemonkey's advice on cleaning the terminals at the grid and checking the fuse. The defroster button in the HVAC control assembly provides a ground connection to a relay located in the underhood junction box. The relay is powered by a 10A fuse. When the contacts close, it provides power from a 30A fuse on a purple wire up to a junction box in the left side of the instrument panel. From there, the power flows on a black wire to the grid. The grid is grounded by a black wire that terminates on the passenger side of the rear package shelf. Check all those connections for power and ground.