Model A1286. Released February 2011 / 2.0, 2.2, or 2.3 GHz Quad-core Intel Core i7 Processor

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Left fan running (over) full speed, Right fan not running.

I was wondering if anyone here can help. My Macbook Pro (Early 2011 15”) left fan is always running at over 7000 RPM (out of an apparently maximum 6200), and the right fan rarely comes on. I think the right fan rarely coming on is due to the machine not being under much stress.

According to TG Pro, and other monitoring software, all my temperature sensors are reporting healthy temperatures in the TG green range, and it can’t seem to pick up any hardware issues.

I’ve reset both the SMC and NVRAM several times. I then replaced both fans (as well as clearing out any dust from the vents) but the issue is still there.

I’m now out of ideas. I figure if it was an issue with the temperature sensors or thermal paste, that it would be reflected in TG Pro saying something was running hot?

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Many thanks!

Answer this question I have this problem too

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Can you post a snapshot of the main TG Pro window showing all of the sensors (you may need to grow the window to see them all)

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Did you clean and reapply fresh thermal paste on the heat sink?

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Screenshot added!

I didn't apply fresh thermal paste. I thought a thermal paste issue would cause the sensors to claim it was heating up?

Thanks :)

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@buddyfuzz - The reason I asked was more on what was altered in the system given the systems age I would have redone the paste which is why I had asked. For now lets not touch it (you hadn't before have you?).

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Nope, haven't touched it!

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At this point I think you’ll need to replace the left fan unit which is on the right side internally (remember you are flipping the system over) Here’s the IFIXIT guide MacBook Pro 15" Unibody Early 2011 Left Fan Replacement and the needed part MacBook Pro 15" (Late 2008-Mid 2012 excluding Mid 2009 2.53 GHz) Left Fan.

Do a good inspection on the logic board looking for signs of corrosion as that could be a factor here.

MacBook Pro 15" (Late 2008-Mid 2012 excluding Mid 2009 2.53 GHz) Left Fan Image

Product

MacBook Pro 15" (Late 2008-Mid 2012 excluding Mid 2009 2.53 GHz) Left Fan

$59.99

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Smc signal for fans speed goes through a data line including a couple resistors. Maybe one or both have gone bad and need to be tested and possibly replaced. It’s not a terribly difficult job but yet it requires some tools, parts and at least some experience in microsoldering, since resistors are very small sized.

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My thought is that something related to the non-running fan is bad, and the other fan is running faster than normal to compensate for the non-running fan.  If the temps are normal, then the compensation is doing its job.

You still need to fix the problem with the non-running fan; but it sounds like you’re ok for the moment.

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I thought this may be the issue as well, so I replaced both fans, but still the same issues remain. The right fan does come on from time to time (I think when needed). I really can't figure this one out.

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As arbaman pointed out above, there may be a resister or something else related to the fan which is causing the fan not to work. Perhaps a temperature sensor is not sending information, thereby resulting in the fan not coming on, because the computer thinks that it is not needed. But since you are getting normal temperature readings throughout the computer, I doubt that this is the case.

If this was a Windows computer, I would suggest installing Speedfan on the computer, because Speedfan allows you to manually set the fan speed. By manually setting the fan speed, the fan might run; whereas the normal processes are not turning the fan on. Here are some alternatives to Speedfan for the MAC:

https://alternativeto.net/software/speed...

I'm not familiar with any of these programs, but I would try something like this if I had a MAC that had a non-working fan.

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@mrjimphelps - I don't think adding another monitoring app is needed here.

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My point was not to do additional monitoring; my point was to see if the app would let you manually turn on the non-running fan.

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Jonny will be eternally grateful.
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