Have you pulled the fuse and hooked an ohm-meter to it to make sure it's not bad, or replaced it just for grins? How about using a volt meter to measure whether or not there is any power at the fuse block. Then check to see if there is a dedicated relay for the blower/radio (if there is, I would think it would be for the entire gauge cluster). If so, test the relay. If all of that checks out, pull the radio and see if you're getting power to it's wiring harness. If not, trace it back until you find the open.