1996 Chevy Tahoe squealing and overheating

Engine Cooling problem
1996 Chevy Tahoe 6 cyl Four Wheel Drive Automatic

My 1996 Tahoe has started making a high pitched noise on start up and accelerating. It also has been overheating once and a while. This morning while taking the kids to school the temperature gage went from low to almost in the red. I had the heater on and it was blowing cold air. After a couple of minutes the hot air finally started to flow and the temperature gage went back down. The tech at the local auto parts store said the noice sounds like the AC compressor is bad and said to run the belt without going in the compressor. The overheating he said was probably the water pump. Does this sound right? I am clueless when it comes to auto repair.