CPU fan running at full speed

Question

Level 1

0 points

CPU fan running at full speed

Hello,

the CPU fan starts running at full speed and does not slow down. I have to power down the computer, unplug the power cord, wait for several minutes and plug it back in to resolve this. Sometimes everything is fine for 2-3 days. Sometimes the CPU fan starts running at full speed after 10-20 minutes again.

This happens at the same time as following entries appear in the system.log.

Oct 20 14:20:55 Flos-iMac-3.local mdworker[19093]: Unable to talk to lsboxd

Oct 20 14:20:55 Flos-iMac-3.local sandboxd[19094] ([19093]): mdworker(19093) deny mach-lookup com.apple.ls.boxd

Oct 20 14:20:55 Flos-iMac-3 kernel[0]: Sandbox: sandboxd(19094) deny mach-lookup com.apple.coresymbolicationd

OS X 10.8.2 (12C60)

iMac11,3

Intel Core i7

2,93 GHz

Boot-ROM-Version: IM112.0057.B01

SMS-Version: 1.59f2

I once installed a clean version of Mountain Lion. That did not resolve the issue. How can I resolve this?

iMac, OS X Mountain Lion (10.8.2)

Posted on Oct 20, 2012 5:30 AM

Reply

Answer 1

rkaufmann87

Level 10

140,376 points

Oct 20, 2012 6:12 AM in response to TheWiener

Do 2-3 SMC resets following the instructions in iMac SMC and PRAM reset. If that does not correct it run Apple Hardware Test in Extended Mode. You may have to run AHT 3 times or so to get accurate results as errors don't always show up the first time. If you get errors then your next stop is an Apple Store or AASP for repair. It is possible you have a fan sensor or fan that may have failed. If your machine is covered by AppleCare then this would be covered.

Reply