My 600 Sq Ft. Patio problem may be your 400 Sq Ft. Solution? I ordered Amazon Mini Split AC/Heat 12000 BTU Klimaire 230 Volt unit.

It’s estimated to handle 200 to 400 Sq Ft area and I’m comfortable it will. I didn’t take into consideration that my area is mostly windows, doors and of course 200 sq foot too large for this unit. I’ve ordered another larger unit and will installed it myself again. If you have an area of less than 400 Sq Ft, this could be a solution for you.  Blows 50-degree air but not enough for 600 Sq Feet. If interested, you can come see it work and what it takes to install. Lots of examples on YouTube. Asking $550.