a/c blows hot air what to do

Get under the dash and work the controls while watching what the control cables are doing. You should be able to see what's wrong if it's a blend door stuck or a cable come loose.

You could also try and getting a do-it-yourself kit from your local auto part store. It would cost you around $30 the kit should include the hose and a can of R134. Its easy to do for first time users.