iMac fan trouble

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Level 1

2 points

iMac fan trouble

I just replaced the HD in my 27 inch iMac. It originally had a seagate 1 tb that crashed, so I went with a 2 tb Western Digital Caviar Black. The seagate had an internal temperature sensor, but the WD has no place for a wire to connect for temp sensing. I shorted out the wire, with the thinking that it would make the fan run at idle speed, and I could use a program like smcFanControl to bump the speed up a bit to keep it cool inside. However, the fan seems to be running full speed by itself. smcFanControl is telling me that my Optical fan is around 3500 rpm, the cpu fan is around 4000 rpm, but the hdd fan is only going 1100 rpm. I reset the SMC by unplugging the machine but it did nothing. Activity monitor says nothing is using any cpu, and there is no disk in the dvd drive. Anybody have any thoughts on this?

iMac, Mac OS X (10.6.2)

Posted on Apr 24, 2011 4:45 PM

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Answer 1

den.thed

Level 9

77,182 points

Apr 24, 2011 7:45 PM in response to joltes

Sounds like maybe you have a problem with the SMC chip, either from shorting the HD sensor or because of another sensor issue? Run the Extended Apple Hardware Test and see what it turns up.

http://support.apple.com/kb/HT1509

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Answer 2

joltes Author

Level 1

2 points

Apr 26, 2011 5:24 AM in response to den.thed

The hardware test shows an error. 4SNS/1/C0000008:TLOp--124. From what I have found so far, that means a sensor failure. Im going to open it back up and reseat all of them, hoping for an easy fix.

To reset the SMC, do you have to just unplug the computer, or do you have to hold the power button for 5 seconds while it is unplugged?

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