MacBook Pro heating up and fan running faster without apps running

Hi All,

I've seen similar issues to mine over the forum, but I believe this is a unique scenario.

I am on a clean installation on Sierra and I do not have any apps running on the machine. But as soon as I log in to the OS, I can hear the mac's fan going crazy and mac heating up. This is quite strange since I dont have any apps installed.

1. I did an SMC rest, NVRAM reset, but none of them helped

2. Checked if its an issue with kernel_task - Used "top" to figure out if its kernel_task, but I cant see any issue there.

3. Opened up the mac to check for dust - Cleaned up the fan (there was not a lot of dust there to begin with)

None of the above steps helped. The next steps I plan to do are,

1. Install istat menus and check fan status

2. Check mac status on diagnostics mode (Command + D on start-up) - see if I can get anything out of it.

Please let me know if you have faced a similar issue or if you have found a resolution to this issue.

Thanks in advance

Answered! View the answer I have this problem too

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Chosen Solution

Re-installing Yosemite resolved the issue.

Seems like its a problem with Sierra.

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That makes no sense!


I haven't seen anything that would lead me to believe this is a real fix.


Believe it or not, it did resolve my issue.

The only thing i did was, moving back to Yosemite from Sierra.


oh, and I installed istat menus, CPU temp and fan speed looks fine. Can't see any issues there. I will report back if I continue to see more issues.


I have a few of these running Sierra for testing for our big roll out. None have had any problems.

I suspect you really have a HD or SATA cable issue here as the stress of upgrading can push a system hard. This series has a known issue with the SATA cable.


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Sadly I suspect your heat sink is bad. You'll need to change it as well as clean & apply fresh thermal paste.

if you do a careful inspection you'll likely see some wetness near the heat transfer tube on the logic board or you'll see a pin hole in the tube.

If you have access to a non contact thermometer or FLER scope you can see the heat is not transferring to the fins.

Once you get the new heat sink with a good digital scale you'll note the bad unit will be slightly lighter than the new unit.

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Thanks Dan.

an installation on Yosemite resolved the issue. Seems like the problem was OS dependent


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Hashan Ranatunga will be eternally grateful.
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