2003 honda civic lx alternator?

Whenever I would turn my heat or anything on I would get a loud squeal from the front. I went and bought a new battery and alternator. I put them in and whenever I turn my lights on it's still going dim while I'm driving down the road it feels like everything is okay. When driving if I turn the heat on I get a loud squeal from the front. I also get it when at a stop idling and when I press on the accelerator it gets louder and then cuts out. Any ideas?

Take the belt off again and turn all the pulleys by hand to see which one is stiff. Fix that one. Take out the fuse for your air conditioner and see the squeal not happen. That means the compressor is dragging the belt.

The serpentine belt tensioner spring is shot. Buy and install a new tensioner from a Honda dealer and your problems will be over.