When The AC Doesn’t Work

Of course the air conditioner always works when its not hot but let the temperature go up just a bit and that's when it doesn't want to work. Can someone help me out with this?

Does anyone know why my ac keeps doing this? It will freeze up and I will turn it off and let it thaw out and then in about an hour its back to the same thing.

Does it need free-on? I have changed the filter. I don't know what else to do.