Fan keep running - AHT doesn't work

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Level 1

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Fan keep running - AHT doesn't work

I have an 24" core 2 duo, 3,0g ghz iMac from 2008, now running OSX vers 9.1. A great machine, almost a member of our family by now.

But a few days ago a fan started to run constantly. I think it is the one located on the lower left side of the machine.

According to a 'Cooler Controller' from the App Store the temp is low and shouldn't need any constant fan cooling (as has not been the cast in the previous years). It just runs at the same middle-speed no matter how many apps are open.

I've tried to reset the SMC as per instructions here at the Apple support site

I've deleted the HD completely and installed OSX from scratch

I've tried to run the AHT - also as per instructions on this site - but nothing happens when I restart while pressing the D key.

I've even tried to vacuum clean any dust away through the ventilator holes on the back side and at the buttom of the iMac.

What more can I try to fix this? - Any good ideas more that welcome!

Michael

Aperture 3, iOS 6.1.4

Posted on Jan 4, 2014 3:46 AM

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Answer 1

andyBall_uk

Level 7

20,516 points

Jan 4, 2014 5:10 AM in response to mkirke

Did you try to run AHT from the original install dvd ?.

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Answer 2

mkirke Author

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10 points

Jan 4, 2014 11:55 AM in response to andyBall_uk

Thanks for the tip. But no, I haven't. I don't have the original dvd anymore I'm afraid..

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Answer 3

andyBall_uk

Level 7

20,516 points

Jan 4, 2014 12:05 PM in response to mkirke

Apple can usually supply replacements for a modest charge, if you call with the serial number.

Also see http://rivenbyfive.blogspot.co.uk/2012/01/download-and-run-apple-hardware-test.h tml since you can download some from Apple and either run from a usb, or replace the hidden /System/Library/Coreservices/.diagnostics folder, then run it directly from the HD.

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Answer 4

mkirke Author

Level 1

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Jan 4, 2014 12:13 PM in response to andyBall_uk

Thanks Andy - will try the download option right away

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Answer 5

mkirke Author

Level 1

10 points

Jan 4, 2014 12:21 PM in response to andyBall_uk

As my model-id is 'iMac8,1' it seems I can't download the AHT version in question for my iMac and will have to call for a replacement dvd, but thanks all the same

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Answer 6

mkirke Author

Level 1

10 points

Jan 5, 2014 3:04 AM in response to andyBall_uk

Andy, I downloaded the Tempetarure Gauge app frorm the App Store.

It clearly shows that it is the cpu fan that runs wild - about 3600 rpm constantly even though the cpu temp never gets above 35 Celsius. None of the other two fans are active and the ambient air inside the machine is just 21 Celsius.

When it get the AHT tool - will I then have the option to turn off or resent that particular cpu fan in any way - would you happen to know that?

thanks,

Michael

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Answer 7

andyBall_uk

Level 7

20,516 points

Jan 5, 2014 7:42 AM in response to mkirke

I see, the 8,1 is missing, even though later ones are listed. Sorry about that.

AHT has no options to change anything, the most it will do is give a specific sensor error.

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