Fan stuck on full

Question

Level 1

4 points

Fan stuck on full

So I just purchased a 2012 macbook pro 17" and love it. There was one issue that i was aware of when i purchased it. The left fan is stuck on full speed. I have downloaded TG Pro and the right fan control works perfectly but the left fan says it is at 0RPM even though it is at full speed, every once and a while it will blip showing 250 RPM but drop back to 0. i can not control the fan speed at all. At least I know that the fan is working and it won't over heat. anyone have any thoughts? I don't have alot money to take it to an apple store.

MacBook Pro, OS X El Capitan (10.11.4)

Posted on Apr 22, 2016 7:28 AM

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Answer 1

Courcoul

Level 6

18,684 points

Apr 22, 2016 7:33 AM in response to Bursjon

First try an SMC Reset and an NVRAM Reset and see if that helps.

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Answer 2

Bursjon Author

Level 1

4 points

Apr 22, 2016 8:48 AM in response to Courcoul

I just tried both of those and neither worked. Now i don't know if it makes a difference but the fan goes to full the second i hit the power button and before the start chime. I am not sure if that means it is hardware related or software. The Macbook has a fresh instal of El capitan on it as well so there is nothing that should be causing it.

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Answer 3

Bursjon Author

Level 1

4 points

May 29, 2016 6:23 AM in response to Bursjon

So I am following up on this issue. I have purchased a replacement fan and replaced it but still it has the same issue. My worry is that it is logic board related. Any suggestions?

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Answer 4

OGELTHORPE

Level 9

57,329 points

May 29, 2016 6:47 AM in response to Bursjon

Run an Apple Hardware Test:

https://support.apple.com/en-us/HT201257

Note that an error free AHT is not conclusive.

Ciao.

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Answer 5

Bursjon Author

Level 1

4 points

May 30, 2016 7:06 PM in response to OGELTHORPE

I attempted run the AHT byt my mac is a 2010, and does not support AHT... is there any way to run a hardware test without the built in hardware test. and without taking it to an apple store?

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Answer 6

May 30, 2016 7:13 PM in response to Bursjon

I don't have alot money to take it to an apple store.

If you have an Apple Store, your visit for an evaluation and testing is free, in warranty or out.

If all you have is an Apple authorized Service provider, they make their own policies. But some have the policy that if your visit results in Repair business, they may waive the exam fee.

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Answer 7

OGELTHORPE

Level 9

57,329 points

May 31, 2016 2:21 AM in response to Bursjon

Bursjon wrote:

I attempted run the AHT byt my mac is a 2010, and does not support AHT... is there any way to run a hardware test without the built in hardware test. and without taking it to an apple store?

Absolutely. A 2010 MBP came with Snow Leopard installation disks and the #2 disk has the Apple Hardware Disk on it. Dust it off and run it.

Ciao.

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Answer 8

Bursjon Author

Level 1

4 points

Jun 4, 2016 2:34 PM in response to OGELTHORPE

I bought this MAC book pro used and do not have the disk for Snow Leppard. Is there any way to get this with out having the disk?

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Answer 9

Bursjon Author

Level 1

4 points

Jun 4, 2016 2:41 PM in response to Bursjon

My partner has a disk for Leopard does that disk have AHT on it?

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Answer 10

OGELTHORPE

Level 9

57,329 points

Jun 4, 2016 3:24 PM in response to Bursjon

Installation disks are model specific so a Leopard disk will not work. You were cheated by the prior owner because he/she should have given the disks when the MBP was sold. Duplicates may be purchased from Apple Customer relations.

You can try to download the appropriate one for your MBP from here and run it:

https://github.com/upekkha/AppleHardwareTest

Ciao.

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Answer 11

Bursjon Author

Level 1

4 points

Jun 5, 2016 6:38 AM in response to OGELTHORPE

Just made the AHT a bootable USB and the code it came back with is "4M0T/4/40000002: Left side-0"

This if from a quick test. I am running a extended test now to see if anything else pops up. Any suggestions on this code?

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Answer 12

Jun 5, 2016 7:32 AM in response to Bursjon

The MOTors on the fans have an RPM output that is read by the software to deduce actual fan speed.

If not fast enough it raises the voltage until the fan is spinning at maximum speed.

I think you may have a bad fan motor on the left side.

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Answer 13

Bursjon Author

Level 1

4 points

Jun 5, 2016 8:35 AM in response to Grant Bennet-Alder

I thought the same thing. But i have a replacement fan and it still did the same thing. I even took the fan from the right side and plugged it in and booted up and still the left side is doing the same thing. in short the right fan is working properly, when i take the right side fan and plug it in to the left side the same issue comes up but only on the left side. Would that narrow it down to a logic board issue?

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Answer 14

Jun 5, 2016 8:56 AM in response to Bursjon

The red and black wires are the voltage, and the yellow wire is the RPM output (if so equipped).

You may be able to trace the wiring and find a bad connection or a break in the wire somewhere.

Otherwise, yes, it's a logic board problem.

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Answer 15

Bursjon Author

Level 1

4 points

Jun 5, 2016 9:21 AM in response to Grant Bennet-Alder

I have not opened it up yet but if it helps every once and a while while i monitor the fan it will flicker for one second to reading like 7 RPM then drop to zero within a second.

Just though i would add every piece of information i had to this.

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