I have an issue with my a/c. It started blowing hot air last week out of the blue even with the temp control set in the mid 50's on the dash. The next day it worked just fine and then went out the following day and has been out since. Had local mechanic check it on Saturday and he said all pressure readings and freon levels within specs. I am in FL and need to get this fixed before it gets hot. Some people have suggested replacing the a/c heater control valve instead of the interior control panel, please advise if this is something I can get to or should have a professional take a look at.

Thanks