Both heating and cooling are provided by the AC splits installed on the walls of most rooms. Each one should have a remote control. They are, in any case, completely interchangeable.
Please do not run the splits with windows or doors open. Also, please switch them off when the room is not in use or you are out of the house.
It is worth noting that running the units in “Dry” mode reduces the room temperature more cost effectively than “Cool” or “Auto” modes. Try it – it may be sufficient.
If you are having difficulties with the splits, there are fans and electric heaters in the hay loft.