They are right about the blend door...although they normally default to hot. If you'll find your HVAC fuse and take it out for a minute or so then replace it, it will also reset. If you are 200 degrees with water in and out of core its not the core.
"But if serving the Lord seems undesirable to you, then choose for yourselves this day whom you will serve, whether the gods your ancestors served beyond the Euphrates, or the gods of the Amorites, in whose land you are living. But as for me and my household, we will serve the Lord.” Joshua 25:15