Why does my Frigidaire Fridge always make a high pitched noise? I think it's about 10 years old maybe 5.... Does it need freon or service?

Motors make noise. You have 4. The evaporator motor in the freezer compartment, the condenser fan motor on the bottom back of the machine, a timer motor located in the fresh food compartment, next to the thermostat, and lastly the compressor itself, located in the bottom rear of the machine. You'll have to determine which area the noise is coming from.
However, I have seen many Frigidaire machines where the problem is in the compressor itself.
If you feel that is the problem, you can call a qualified Frigidaire service tech to verify that. If that's it, your looking at a very pricey repair. Lets hope it's one of the others.