96 crown vic voltage meter

Hi, I'm hoping someone can please give me some advice. I have a 96 crown vic with 181,000 miles. My voltage meter keeps dropping below the half way mark when I turn on my heat or defrost. It happens when I stop for a red light and car is in gear. It sounds like its when it idles down. Also when I start the car its squeeling like a belt and continues until it heats up. The voltage meter dosent drop as long as im moving. I had the battery tested its reading 14 volts. I replaced the alternater, and the ideler pully. Im on dissability and I'm running out of money and patience. If anyone has any advise for me I would greatly appreciate it! Thanks

Well, the squealing sound is possibly a belt slipping (which isn't that hard to replace), or it could also be one of the pulleys going bad. I changed my belt twice before I finally pin pointed the idler pulley had a bad bearing. Go to www.RockAuto.com for inexpensive parts, usually cheaper with the shipping than buying it from OReilly's or AutoZone.