Heater, Idiot lights and alternator failure?

I have a 1987 Trooper with the 2.3, 5 speed. I went out Sunday and started it up. I noticed that I no longer have any power to the heater fan or rear window defroster switch. I noticed that the low fuel, battery and brake idiot lights remained on. Everything else worked, i.e. headlights, wipers, radio, and cig lighter. Everything worked the day before, no problems. Is the heater fan and rear window defroster switch not working a sure fire sign of alternator failure? The alternator was not making any strange noises or anything. Is it common for a alternator just to go out without any kind of warning?:confused:
Thanks. .

hello jim,no not really on alt. question.have u checked fuses???

I checked all the fuses that I could find, and they were good. I had a '87 before, and there was a 'hidden' fuse buried way up under the dash. I found this hidden fuse when I sunk a screw into the underside of the dash when installing a radio. This caused the heater fan not to work. I looked for this hidden fuse and could not find it. But why would the idiot lights stay on? Even after releasing the e-brake, the light still stays on. The fuel and battery light would come on at start up but then go right out like they are supposed to, but now they come on and stay on as well. So, are the heater fan and rear window defroster on the same curcuit? Even though, my Trooper is 'old school'(not computer controlled), would a bad alternator prevent big draw, high amp items from working? How would this affect the ignition?