Aircon only cools on low

ford fiesta 2007. My aircon only blows cold air on the setting 2. when i put it higher it just blows out warm air. after ive put it on high & i turn it back down to low it doesnt work for like a day, then itll go back to normal. What could cause this?

It might be low on freon or a blend door might be malfunctioning. I’d take it to a good a/c shop and have it checked.