On Tuesday, December 3, 2019 at 2:05:26 PM UTC-5, M. L. wrote:
I have a broken air conditioner that plugs into my 220V USA wall
socket. Its prongs look quite different from typical 120V appliance
prongs. Before next summer I'd like to buy a 120V portable room air
conditioner. Is there a converter available that would allow me to
safely plug the 120V 3-prong socket portable air conditioner into the
220V outlet? Thanks.

Why not buy a 240v unit so you don't have to rework/run new wires?

I'm having trouble finding a 220v "portable" air conditioner that's
designed and priced for a bedroom-sized area. I was hoping there would
be a converter box available that could make my American 120v appliance
compatible with my American 220v socket.

When we lived in Europe we used transformers to run American 120V appliances on German 220V power.

But one large enough to handle an AC unit is going to cost a lot, probably more than the AC unit, and they are massively heavy.

With German power we also had to worry about 50 Hz vs 60, but you're on American power so there should be no issue.