Heater works after being off a while

Question

The last week or so My wife has noticed that theheater wasnt working. So she turned it off for like an hour then turns it back on it will work till it hits Set Point then kicks off. When it kicks back on again it blows cold air. She then has to proceede to turning it off again. What coud be causing this?

Weather king Model # WRKA-A030JK06E