This is public housing. Some people simply can't afford AC as the city isn't paying for utilities in all buildings (it does in some). Some people you can see have an AC unit in the bedroom instead of the living room and so on.

But there is also many years long backlog on repair work required for public housing units by the NYC Housing Authority that does result in apartments sitting empty. The current estimate is its $80 billion in repairs backlogged https://comptroller.nyc.gov/newsroom/nyc-comptroller-audit-f...

With 6000 units sitting on that backlog https://gothamist.com/news/nycha-has-nearly-6k-vacant-apartm...