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Model A1418 / Late 2013 / 2.7 & 2.9 GHz Core i5 or 3.1 GHz Core i7 Processor

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Fan noise not going away even after putting original HDD back again.

I have iMac : Core i5 2.7, 21.5-Inch, Late 2013

  • I tried to upgrade HDD to SSD
  • When I upgraded to SSD I started having fan problem: the fan started going at full speed.
  • Since I don't necessarily need SDD (and not sure how reliable are apps that control fan speed), I reverted back to originial HDD that came with iMac
  • Unfortunately, even with original HDD back in its place, the fan problem is not going away.

From what I have read, putting original HDD back should have solved the problem but apparently that is not working for me.

Any ideas?

Answer this question I have this problem too

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3 Answers

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At this point I think you need to identify which sensor is either not plugged in or not working. I would recommend downloading this app: TG Pro it should show you what sensor is failing.

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I will definitely download the app this evening.

BTW, when I disconnected the original HDD there was only one cable that plugged into it. I reconnected the same cable when putting the HDD back again. I did not see any other cables. None of the instructional videos mention another cable either.

Is thermal sensor connected via a separate cable ? Where would I find it?


I'm thinking the display sensor might be the issue. But it's best not to guess :-)


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Here is the parts you'll need:

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Thanks. I will get the cable with thermal sensor. (1) So what do you think happened ? Somehow thermal sensor got damaged? (2) Do I need drive adapter bracket? My HDD (and SSD) both fit perfectly in the original rubber padding and drive space.


I just saw the thermal sensor cable again... It says it is for 27 inch iMacs.... Would it work in 21.5 iMac (mine is late 2013) ?


Opps on me :-( I could have sworn you listed a 27" model.

Nix the parts! Your 21.5" model uses a 2.5" drive, very different besty inside.

What did TG Pro show you?


TG Pro did not show HDD temperature until I went into the 'preferences' and enabled 'check hard drive temperature using S.M.A.R.T.' Once I enabled it, it shows the temperature of the HDD.


Thats correct, 2.5" drives only offer SMART access to the HD temp.

Can you post a screen capture of the main screen of TG Pro so we can see what you see.


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shutdown your computer, unplug the plug, and then while the computer is unplugged, hit the power button.

then plug it back it, and hit the power button to start it.

then when the screen turns on, immediatly hold command alt p r

until the computer screen goes black and you hear a chime. then release the keys and tada!

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Called 1. SMC reset, 2. PRAM reset.


I tried both but no luck :-(


Any other suggestions ? Do you think software solutions like (Mac Fan Control ) are reliable ?


I don't like the software solutions as time has shown us they don't offer a good long term fix. Either the logic board is thermally shocked and/or the fan burns out from being over rev'ed. See below on the parts I use.


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Dhaval Shah will be eternally grateful.
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