You need to call an electrician. First thing you need to check though, is your AC unit actually 220V or is it 110V? If it’s 110v and your unit draws too many amps, you need to unplug everything except the AC from that circuit. If it still blows the fuse/breaker, you’ll need an electrician to identify the wire gauge to know if it’s possible to change the breaker and outlet or if you’ll need a new wire ran. To answer your question though, it is possible to change the outlet to a 220 plug but you need to also identify the white wire as being hot. You’ll need to make sure it has the right gauge wire for the load. You’ll need to make sure it’s the only outlet or light on the circuit. You’ll need to identify the neutral wire inside the panel box, separate it, label it and install a new double pole breaker. You’ll also need to make sure each wire is on a different leg in the panel box, otherwise you won’t have 220v.