When I closed the lid on my MacBook Air Tuesday night, I noticed that the Apple logo was still glowing. The backlight hadn’t turned off for some reason. After several seconds, though, it did finally switch off and I turned away to get ready for bed.

Beep-beep-beep… beep-beep-beep… beep-beep-beep…

The Air was beeping at me in a way I’d never heard before. I went back and opened its lid.

Beep-beep-beep… beep-beep-beep… beep-beep-beep…

The screen didn’t come back on, and the beeping didn’t stop. By this time, the Air’s fan had started spinning up and was getting louder. I held down the power key until everything quieted down, and then pushed it again to reboot.

Apart from complaining that I hadn’t shut it down properly, the Air booted up more or less normally. I thought it might’ve taken a bit longer than normal, but I’m not a good judge of “normal”—I almost never reboot that machine. Since everything seemed to be working fine, I closed the lid again, hoping that the reboot had fixed some temporary software problem.

Beep-beep-beep… beep-beep-beep… beep-beep-beep…

Shit. I wouldn’t be going to bed for a while.

I went through the usual magical incantations: resetting the NVRAM (the modern-day equivalent of what us old-timers still call the PRAM) and the SMC. Nothing. I tried to run Apple Hardware Test to get a diagostic rundown, but AHT told me it couldn’t run on my machine.

Googling “three beeps mac” led to pages that weren’t reassuring: that sound is associated with bad RAM. But everything I saw about it said that sound was part of the startup sequence, and my startup always went fine. I heard the sounds only when closing the lid. And whenever I heard the sounds, I’d have to shut down and restart the machine.

I tried putting the Air to sleep before closing the lid, but that didn’t prevent the beeps. The only way I could avoid them was to shut down the computer first.

So I scheduled a visit to the Genius Bar at my local Apple Store for Wednesday after work. I was assigned to Julio, who listened to my tale of woe and, after confirming that I had a current backup, started running the special diagnostics available to Apple techs.

The initial diagnostic test, which takes about 10 minutes, came up clean. RAM, logic board, SSD—everything was fine. Julio had told me ahead of time that this test was not the last word; it’s run to find the more obvious flaws in a system. Given that my Air seems to be running fine except for this lid-closing problem, I supposed it’s not surprising that a superficial test didn’t find anything wrong.

Julio then took the computer into the back room where he’d be able to hear the various noises it made when the lid was closed. The store wasn’t as loud as it was the last time I visited the Genius Bar, when a half-dozen guys yanked iPhones out of their sockets and ran out, but it was way too loud to hear a fan spinning up. He also took the cover off, did some poking around, and consulted with the other techs back there.

The upshot: get a new logic board. $400+ if done in-store, $280 if done off-site, but with a 5–7 day turnaround.

This is, I should point out, a late-2010 MacBook Air. Under normal circumstances, I wouldn’t even consider putting money into a nearly five-year-old machine that I was planning to replace before the end of the year anyway. However…

As I said last week, iOS 9 has made me think my next mobile computer should be an iPad. If that’s the case, I’d still want to have a Mac around the house, and the Air would work nicely as an occasional computer for archiving photos and doing the other things that iPads still aren’t good at. $300 doesn’t sound too bad when you consider that I’ll be getting a new processor,1 RAM, and SSD along with the logic board.

Also, if I’m going to go with an iPad, I don’t want to buy the current iPad Air 2, I want to get whatever’s coming out in the fall.

Luckily, my MacBook Air isn’t a mission-critical machine. I can live with it as it stands while I figure out what to do.

  1. Yes, it’s really an old processor, but you know what I mean.