Fan air and radio no work - 1996 Cadillac DeVille

Most likely a blown fuse. Fuse box will be either under the dash by the steering wheel or under the hood. Once you find it, remove the cover and on the back there is a diagram showing the corresponding part to each fuse. If you don't see a fuse that says " radio" or "fan" or something that resembles it, you can do two things to find it. 1.) if Available, check vehicle manual under fuses, it will tell you which one 2.) if no manual is available, make sure vehicle is off and check all the fuses. (Sometimes manufacturers use weird names that the consumer would have never guessed it was to describe something so simple) You only have to check your garden variety fuses. There is no need to check the oddly shaped ones or the giant fuses. Radio fuses are common to burn out and easy to replace