I have a 2003 Buick Rendezvous and this morning I went to turn on the rear defogger and it did not work. The on indicator light did not light when I pushed the button. Also, I tried to turn on the A/C switch next to the defogger switch and that did not work either. Both switches seem "dead". Lastly, above these two switches is the heater/front defroster ****, and this also seems to not work. I checked all the fuses, and they are OK. Could this be a relay?