New York City Housing Authority General Manager Vito Mustaciuolo actually says he’s “proud” of his agency’s progress since last year in reducing heat and hot-water outages. That sort of pride is part of NYCHA’s problem.

After all, as The Post reported Monday, 87% of its 174,000 homes — almost nine out of 10 — lost heat or hot water at some time last winter, with an average outage lasting nine hours, according to data obtained by the Legal Aid Society through a Freedom of Information Law request.

If reaching that point marks notable “progress,” NYCHA residents may be in worse trouble than they know.

The agency’s top brass note that last winter’s 3,559 outages (2,341 for hot water and 1,218 for heat) were actually 1,000 fewer than the previous winter. Yet that’s a pathetically low bar; no one should be “proud” that 339,000 people got zapped.

“When I went to the back of the apartment, it was like going into a walk-in freezer,” said one tenant, Tomasita Santapau, 72.

The stunning numbers are yet another reminder of the outrageously dismal conditions at NYCHA housing — and its dysfunctional management. Recall that residents have also had to suffer through an almost biblical list of plagues: broken plumbing that seeps liquid, lead paint that can poison children, uncollected garbage that climbed as high as 14 stories in trash chutes and brought rat infestations.

Yes, NYCHA has been strapped for funds. Needed repairs will run into the tens of billions, and no one is fully sure where it will all come from. It also faces a web of union regulations and work rules that can make it hard to fix problems quickly.

Plus, its new chairman, Gregory Russ, took over only Monday; NYCHA’s been largely in limbo ever since former Chairwoman Shola Olatoye was forced to quit last year following a lead paint scandal, and since acting boss Stanley Brezenoff was ousted under a deal with the feds.

Russ is the first permanent boss NYCHA has had in 16 months. Clearly, he has his work cut out for him. His first task? Making clear to staff that outages that hit 87% of NYCHA apartments are nothing to take pride in.