They're called PTAC (packaged terminal air conditioners), and yeah, it costs a lot to repair or replace them. We opted to replace both our units because, to repair them, they would have to pull them out, take them to their shop and we'd be without units for a week. So we went with two new units.

Our new units work OK, but I think the older freon ones worked much better... I kinda wish we'd gotten the compressors repaired instead of replaced them. I'm not a big fan of the digital units either. I talked to a few others in the building who have experienced the same.

Ask your super, they probably have a couple vendors who they prefer using. I don't remember who I used but they did a good job, though now that I think about it, one of the units was damaged in transit so they had to return two days later with a replacement.