These things are along the same lines as a Window AC unit.
Back when I was a young feller, just about the time the earth was cooling, I was working in the Middle East in a desert camp. We had scores of window AC units and used to repair them on a Regular Basis. There was no such thing as new ones to be had.
In today's world, I would not ask a refrig tech to work on my roof AC knowing what it takes and the cost involved.
Think Bic Lighter,,,,,
2019 Unity LTV CB, pushed by a 2013 Honda CRV, BlueOx Baseplate, Aventa Bar & Patriot Brake