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2.5 GHz dual-core Intel Core i5 processor (Turbo Boost up to 3.1 GHz) with 3 MB shared L3 cache.

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MacBook fans work but won’t spin up; computer overheats and turns off

Inherited a 2012 13” Retina MacBook Pro (Model A1425) running MacOS Catalina. It’s in decent condition but has a weird problem - the fans don’t turn on by themselves so it just overheats and shuts down after a few minutes.

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If I run Macs Fan Control I can turn on the fans manually and the system cools down and runs no problem, but I need to wipe the system and reinstall MacOS so I need to figure out how to get the fans working as ‘system controlled’. I stupidly started the system restore process before fixing this so now I’m stuck without a bootable OS because every time the system starts to reinstall MacOS it overheats and shuts down 🤦🏻‍♂️

Here’s what TG Pro shows when idling:

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So far I’ve tried:

  • Resetting SMC
  • Resetting PRAM
  • Starting in diagnostics mode (won’t start - gives me a command line error ‘Cannot Load "EFI/Drivers/TestSupport.eft*’ - I think Apple broke it for Catalina

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All the internal temp sensors seem to register correctly so I don’t know why the fans aren’t spinning of their own accord. Maybe there’s something in settings I can reset or edit whilst in safe mode to get the fans working properly again??

People asked for a photo of the inside. I can’t see anything visually wrong with a cursory glance; haven’t removed the heat sink yet as to my mind if the sensors are reporting temps correctly and the fans are both spinning when I manually set them then the problem doesn’t lie in the heat sink/paste, though I could always replace the latter anyway…

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More likely the heatsink coolant has leaked out so the heat is not transferring to the fin area for the fans to exhaust out.

Heat issues can be hard to nail down. I find a thermal camera can be helpful.

Also be careful re-applying the thermal paste! I often encounter people over doing it creating a big mess and a more expensive repair needlessly. It only takes a very small amount of TIM for the task! To help you see how little is needed take a small square the size of the chip of one layer of tissue paper. Now wet your fingers and roll it into a tight ball. Even this it too large!

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36 Comments:

You think heatsink coolant or a lack of thermal paste could be a cause for fans not spinning up? I have doubts about that because as I can see all my thermal sensors seem to be reporting correctly, it's just that for some reason the system doesn't DO anything with that information, namely spin up the fans.

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@peanutturner have you tried replacing the fans or the thermal paste. If the thermal paste is original to the device that might be the issue. This could be caused because the device is 11 years old and is no longer supported by Apple anymore. @beanman56 @hellomacos @danj anything you could suggest to this user or help them solve this problem. I suggest you contact @beanman56 or danj they could help you.

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@macbookuse38039 - I was looking at the delta between the air flow and the CPU as the temp levels noted are not excessive. That’s not to say there isn’t an issue just not enough to argue with the sensors or SMC being the issue, SMC is controlled within the systems firmware not within the OS. We only have a window to the values and can over ride the fans. The temp-RPM slope is strictly within the firmware. One could argue Apple set it too low as Steve hated fans whooshing sound.

Experience tells me to check the heat sink. But how? You need a good medical scale and a second known good heat sink to compare the weigh. That’s how we did it as ell as doing a good inspection of the heat pipes.

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@macbookuse38039 - as the fans RPMs are registering I don’t think that’s the issue. But the right fan maybe bad as it’s stuck at 2k. I would run the onboard diagnostics or use TG Pro’s diagnostics function.

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