Chosen Solution
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?
Many thanks!
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.
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.
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.
