The previous owners had moved the entire heating and AC system when they added onto the house. They had done a kind of half-assed job, and experience with other parts in the house leads me to believe that they got used parts from some junkyard or estate sale. For instance, the heater/AC in the guest room (which is dead) was from a former hotel. They don't even make the parts for it anymore, and so when it died, they said we'd have to replace the entire unit, and since the unit is part of the wall, that's going to be some extensive job. When Anya lived there, she had to heat the room with a floor heater, and cool it with a standard window unit. Since no one lives there now, that's low on the list.
Ah, to be a homeowner :(