Can I switch the end on the power cord on my fridgedair air conditioner from a 220 to a 110... the head of the cord is screwed together not molded

No, the air conditioner needs 240V to run.

The AC is rated for what voltage? I'm a bit confused as to what you are trying to accomplish.

If the AC is made for 220v then it needs to stay at that voltage. You will need to run a 220 volt line or if it's a dedicated line (single outlet) then you can just make the outlet into a 220 volt line by putting in a double-pole breaker so that you have two hot wires with a new outlet as well.