The MTA is feeling the heat from sweltering subway riders.

Online complaints about steamy cars are way up, with 714 gripes pouring in via social media from April to June, compared to 380 complaints during the same period last year.

And despite Chairman Joe Lhota’s April vow to “make sure there are no hot cars,” the transit agency admits there are about 100 cars, or roughly 2 percent of the fleet, with busted A/C on an average day — about the same as last year.

“Why do @MTA and @JoeLhota think so little of the people of NYC that they have so blatantly broken their promise from just two months ago?” Twitter user @MJHBDQ seethed on June 19.

As part of his spring promise, Lhota explained that “we’re looking at each and every one of our air-conditioning units throughout the entire system and refurbishing them and getting them ready.”

The MTA is still trying to look on the bright side.

“Ninety-eight percent of the 5,356 subway cars in service every day have working air conditioning, but nobody should suffer through a hot car in the summer, and we’re fighting hard against heat waves and an elderly fleet to fix those last few stubborn cars,” Lhota said in a statement to The Post Thursday.

The agency said workers have repaired more air-conditioning systems this summer than last, though it did not provide numbers.

The MTA does temperature tests in 90 to 95 percent of its cars every week. It found 46 cars with malfunctioning A/C during the last week of June – up from 39 during the same week last year.

Riders stuck on balmy cars during this month’s heat wave said one broken air conditioner is too many.

The J train was stiflingly hot for Haven Miller on Thursday and Friday as she commuted from the Myrtle Avenue Station in Bushwick to her Financial District job around 9 a.m.

On Thursday, she spent the entire ride in a hot car. On Friday, she said her J train car was cool when she got on, but abruptly heated up mid-ride.

“It became so unbearable that a passenger pried open one of the windows,” said Miller, 23.

The MTA said Thursday it has hired 190 new workers, in part to work on the hot cars.

Additional reporting by Danielle Furfaro