If I, as a typical borrower, were looking at two identical houses, one with working installed AC and one without, at similar prices, I would buy the one with working AC.
If the house with no AC were 5- 7k cheaper, I would choose the other house, because it is still a cash outlay and a PITA to install. That is why marketability can be impacted and not just price enters into it - depending on the market, of course, but a home without AC might take twice as long to sell, or have to offer a concession, etc.