1997 Ford Thunderbird Overheating and Schreeching noises.

I recently had my thermostat replace water pump and hoses replaced about six months ago. I have been checking the coolant and it is always full. When i had the waterpump replaced it stoped overheating. 2 months ago it started overheating again. When i turn on the ac or the heater it goes back down to normal, although now there is a schreeching noise when i drive when i am in idle and other times. The noise sounds like a skill saw but way worse with a slight screech. I really dont know what to do. do you have any suggestions.