The doors to the Princeton Public Library’s Community Room aren’t normally open to Hinds Plaza. But on Monday of this week, day seven of no air-conditioning in the building, the doors were flung wide despite the beginnings of a drizzle outside. The few people listening to a man at the lectern sat fanning themselves in the steamy heat.

A 4,200-pound compressor unit is at the root of the problem. The library is replacing the existing compressor in it’s nine-year-old building, a process that is taking longer than expected. But a measure of relief has arrived: Some temporary units were installed Tuesday while work on the compressor continues. And library executive director Leslie Burger is hoping to have the issue resolved by the end of this week.

“Several times last summer, the compressor unit that runs the air conditioning system failed. After doing trouble-shooting and diagnostics, the recommendation from our contractor was to replace it,” she said Tuesday. “So it took a while to secure a commitment of funding, and then to put it out to bid according to state requirements. Once we did all that, then it was 10 weeks to manufacture the part.”

The part finally arrived, and the installers were scheduled. “We knew we’d be running close to cooling season, and then everything took longer than we expected,” Mr. Burger continued. “Last week was when we could get the compressor and the installer in the same place. Unfortunately, that happened to coincide with the worst weather.”

Hours have been curtailed at the library as the temperature and humidity have risen. The building was not open on Sunday except for one program, and closed at 2 p.m. Monday. It was scheduled to remain open until the normal closing time of 9 p.m. on Tuesday.

Attendance was noticeably down on Monday afternoon. The parking garage, normally packed by lunchtime, was filled only to the second level. Fans whirring inside the building were doing little to relieve the heat. But not everyone was bothered.

“When you’re on the computer, you don’t really notice it,” said Archer Ayres, 8, whose mother, Blair, read in a chair nearby. While somewhat more uncomfortable than her son, Ms. Ayres was philosophical about the situation.

“It’s not as bad as it could be,” she said. “It reminds me of being in Manhattan, where I used to live. You just deal with it. This is an amazing library, so how can we complain? We’re spoiled. We can tolerate a little unpleasantness.”

Ms. Burger said the goal, while the work continues, is to keep staff and customers as comfortable as possible. “This was obviously not our plan, but that’s the way it worked out. We could have waited, but then we ran the risk that it could break down. It’s a delicate balance. But people have been very understanding about it.”

—Anne Levin