oaktons11

Since the weather has gotten cold (last 3 months) my 2000 Camry has had a loud screeching belt problem. About the same time, my steering wheel would lock up in the morning or after my car has been sitting for a few hours in the cold. I got the power steering pump replaced (ouch!) and the sound went away for about a week. Now it is back, but I have notice one thing, it seems to be louder when I have the heat or front defrost on. Now it seems that the air is not as warm as it was. Could it be the compressor, a belt, something else power steering pump related, or just something else? Can I try and tighten the belt by myself? If so, where is the compressor and how do I do it? Thanks, Brian