83 K5 Blazer 350 4x4 used extensively off road. When I have the headlights, wipers, and the defroster turned on to high the voltage meter reads about 8.5. If I turn the defroster fan off the volt meter will slowly come back up to 14. Even if the wipers are off the meter goes low. The alternator is only 1 maybe 2 years old. I've checked/cleaned the connections on the alternator and battery which were not bad but I cleaned them anyways. Battery cables are in good shape with no corrosion. I even added an extra ground strap from the battery to the cab. I don't know much about electrical stuff but with the blower motor being almost 20 years old could it be going bad and would it cause the drain on the alternator? The fan is still responsive to the switch changes between speeds and still blows a good amount of air. It only does it when the fan is turned up to med-hi and hi. Also the wipers go slow occasionaly. The wipers have no effect on the volt meter unless the blower motor is on as well. Once again any help would be greatly appreciated.