charging issues and belt noise

after getting my sc on im having problems with electricity. at idle i make 14v no problem cause i have a 3g 150amp alt. when i turn on my heater the voltage jumps around. at idle the voltage drops to 10 for just a second then goes back up to 14, 10 seconds later it drops to 10 and the cycle continues for as long as the heater/ac is on. i used to have this problem before when i had the stock alt but this only happened at idle when my electric fan kicked on. now even when i m driving at 2200rpm the voltage still goes down to 10v.....where the hell is my power going?
now for the belt noise. when i first fire up my car the belt squeels horrible for about 3 seconds and the sound goes away. never makes a noise after then UNLESS i turn the a/c or heater on. if i turn on the air while im driving im fine but as soon as the rpms get to about 1200 or less the belt screams. then i hit the gas again i can go all the way up to 3000 and the screaming continous. but if i turn the heater off the sound goes away imediately. wtf? none of my accesories are siezed and they all apear to be in alignment. i took a straight edge (ruler) and checked to make sure none were cocked a bit and they all seem fine.
whats weird is that although the sound happenes when the heater or a/c is used, the belt is leaving black powder down by the alt. (the alt is at the bottom now due to the sc.
could it be a cheap belt? and if it was that doesnt explain the charging issue and how the volts cycle like crazy. the alt is brand new. about 500miles on it