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MBA fan runs at higher RPM after fan replacement

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paleshadow

macrumors newbie
Original poster
Nov 11, 2010
7
0
Hi all,

A few months ago I had to replace the fan in my MBA (rev D). I've noticed that the new fan seems to spin up to a higher RPM with much greater frequency than the old one did. (For instance, as I've been writing this post, the CPU has been 95% idle, the CPU temp has been in the low 70s C, and the fan has been running noisily at 4000-5000 rpm.)

I'm acutely aware of fan noise issues because this is my third MBA. My experience for the first year of owning this machine is that it had run much more quietly than the previous two machines, and was also greatly improved in terms of the fan slowing down after the end of heavy usage. Now it's like I'm back to running a rev B.

Any thoughts on what could be going on here?
 
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paleshadow

macrumors newbie
Original poster
Nov 11, 2010
7
0
From Apple (at an authorized repair center, not Apple Store), under warranty.
 
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bp1000

macrumors 65816
Jul 7, 2011
1,476
185
I'm not sure what rev d means but I have a MBA 2011 13" i5 1.7ghz and if I let the computer sleep without ac power and hours later plug in the ac adapter and wake the computer it will make the fans run loudly until I reboot, or possibly let it sleep and wake again with ac still connected.

It's a very annoying bug for me, I wonder if its something to do with the new fans and logic boards.

If you have a different year laptop then perhaps you could ignore all this :)
 
P

paleshadow

macrumors newbie
Original poster
Nov 11, 2010
7
0
Skoopman said:
The heat sensor might be nuts, try resetting the SMC.
Click to expand...

I've tried this, of course, but it doesn't seem to make any difference -- at least, nothing that I can distinguish from the effect of just shutting down for a few seconds and then restarting. After a restart it'll happily run with the CPU in the 70s and the fan at 2000 rpm. But once the fan is up to 4000-5000 rpm with the CPU in the 70s, it doesn't wind down any more.
 
S

Skoopman

macrumors 6502
Sep 24, 2011
318
2
I heard of that problem before, there is nothing you can do I am afraid, it is probably a thermostat/temp sensor failure. Take it back to Apple and show them the problem, they should replace it.
 
seveej

seveej

macrumors 6502a
Dec 14, 2009
827
51
Helsinki, Finland
paleshadow said:
Hi all,

A few months ago I had to replace the fan in my MBA (rev D). I've noticed that the new fan seems to spin up to a higher RPM with much greater frequency than the old one did. (For instance, as I've been writing this post, the CPU has been 95% idle, the CPU temp has been in the low 70s C, and the fan has been running noisily at 4000-5000 rpm.)
Click to expand...

I do not have a Rev D (isn't that the last C2D model), so I cannot check the temps, but my guess is that the fan replacement has somehow "dislodged" the heat-pipe-like arrangement the MBA has, thus lowering cooling efficiency, raising temps and raising RPM's.

To the best of my knowledge, the temperature sensor should not be affected by a regular fan swap and if it was entirely broken, the fan would scream all the time.

In any case, take it back to the service center which did you the disfavor.

RGDS,
 
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