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1.8GHz dual-core Intel Core i5 (Turbo Boost up to 2.8GHz) with 3MB shared L3 cache

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Temperature Dependence of Mac Air (Mid 2012) On Startup

Hi There,

I bought this Mid 2012 Mac Air about that same time, and it has been a wonderful computer. A total trooper. I have replaced: the keyboard, battery, Airport card, power outlet/charger, and now even the motherboard. Most of it was my fault: I’ve spilled liquids on it at least 3 separate times, and for the most part, it has still delivered exceptional service, in spite of the reckless treatment.

So now, I swapped my i7 2.0 GHz / 8 GB Mobo for the i5 / 1.8 GHz / 4GB Mobo, after my latest spill. I got the used 1.8 GHz board off of Ebay for $150, which I would consider a good deal. It worked out of the box, without really any perceptible impact on performance for day-to-day activities. However, I noticed that on occassion the new motherboard would have fits where it would not start up. It would take 5-20 cmd+ctrl+power hard resets in order for it to boot correctly. The problem seems to have evolved, so now that if the laptop is at all warm, then the computer cannot restart. I recently updated the OS to High Sierra 10.13.6 and it wouldn’t boot up for days. I thought it was lost. Surprisingly, though, I had this theory that the computer seemed to boot better when it was cold. So I put the laptop in the fridge for an hour, pulled it out, and it started up as if nothing ever happened. I have repeated this episode maybe 10+ times now, so I am certain that the issue is reproducible. The funny thing is that, once it is booted up, the computer works totally fine! But due to its temperamental state, the computer cannot be used mobile, and has been relegated to use as a desktop only.

So the fact that the computer won’t start if it is warm (temperature-wise), suggests there is some component on the board that is physically damaged, or on some borderline of tolerances. I have no idea if it is possible to troubleshoot this. I haven’t looked to see if I can observe visually any damage on the board. But, since it just fails to boot, but the computer itself works fine afterward (even when warm), I was wondering if there was a way to manipulate the hardware, perhaps disable some checks to prevent it from failing to startup?

I know this is a longshot, but I would love to hear what you think about my issue. The alternative is to just buy another 1.8GHz/4GB mobo and be done with it. But I wanted to see if I had other options first.

Thanks! Dave

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Here’s an update—

I have completely replaced the logic board on the Mid-2012 Macbook Air and the issue has not gone away. This implies that the issue is related to another component.

So is it the display or the I/O board? At first glance, it seems that the display is at fault, because you don’t get a picture after you press the startup button, despite the fact that you hear a chime. However, the fact is that when I put the computer to sleep while it is warm, then the computer will not wake correctly, and also is incapable of restarting. This wonky behavior leads me to believe that a software check is involved—e.g. probably not a result of a faulty component in the display itself. So I am looking at the I/O board as the root of the issue, either because a temperature sensor or discrete component such as capacitor or resistor has some poor connection, or has fallen out of spec.

The search continues!

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@davewhite agreed on the I/O board. Also, connect an external monitor just to rule out issues with the dispaly.

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I have replaced the logic board, now the I/O board, and yet the issue still remains. So it is something inside the display assembly that is causing this issue. This is extremely unfortunate, since that’s the most expensive component to replace, there are few pre-owned eBay models w/o screen damage (if trying to scavenge from the “parts only” as-is category), and its also the most difficult piece to work on. Unless I can find a good A1466 13” screen assembly to drop-in, it looks like I may be in the market for another Mac Air. I am not confident that dismantling and trying to debug the actual board will be fruitful.

If I buy another Air, it will probably be a used A1465 (11”) from Mid 2012 to 2015—the specs are virtually unchanged from the new Mac Airs, the new OS (Mojave) is supported, and you can get for $1000 less!

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Im sorry for asking so late but I hope it can help someone.

I had this issue in my Mid 2012 1,8 GHz Intel Core i5 Air and in my case, it was a faulty sensor in the board. Constant fan, it worked VERY slowly. Activity Monitor was telling me that a process called "kernel_task"was using 87-93% … Apparetly it´s a common issue in certain Airs and MBPs.

I got it fixed by an independent repair , $120 aprox, and it works like new.

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dave white zal eeuwig dankbaar zijn.
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