Mac Mini (Late 2009) "Hard Drive Bay 1" Sensor WAY hot

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Level 2

247 points

Mac Mini (Late 2009) "Hard Drive Bay 1" Sensor WAY hot

I recently purchased a Mini late 2009. I also increased the RAM to 4GB and replaced the stock hard drive with a 500GB unit. Problem now is that the fan (left fan runs constant at 7,400 RPM, right fan not running at all, case ambient temp is 33C and room is 72F with good ventilation) tends to run constantly (loud). I installed Temperature Monitor and can see why the fan is constantly running (the machine thinks it is about to melt on just the one sensor):

http://twitpic.com/rhfsj

I find it very hard to believe the values from this sensor as the differential compared to the other sensors is extreme and all the other sensors would seem to agree with each other. Perhaps I need to move the sensor (it is affixed directly to the rear of the replacement drive and maybe is on a hot spot?).

Powermac G4 Dual 1Ghz Quicksilver, Mac OS X (10.5.7), 3.5 Tb harddrive space, 1.25G RAM.

Posted on Nov 29, 2009 11:27 AM

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Answer 1

Dah•veed

Level 9

64,639 points

Nov 29, 2009 8:30 PM in response to Cobber 99

A Mac mini only has one fan. 33°C is actually a very good temp. Mine runs at about 43°C.

Perhaps a reset of the System Management Controller is appropriate.
1. Power down and disconnect all cables; power, USB, Ethernet, FireWire, etc.
2. Wait at least 15 seconds.
3. Reconnect the power cables and a USB keyboard and mouse.
4. Restart. After the Mac is fully booted you may reattach all hot connectable peripherals.

Dah•veed

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Answer 2

Cobber 99 Author

Level 2

247 points

Nov 29, 2009 9:37 PM in response to Dah•veed

I tried the procedure you posted, but as soon as I turned it back on, same deal - full fan noise and wild temperature readings from just that one sensor:
http://twitpic.com/rk13y

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Answer 3

Dah•veed

Level 9

64,639 points

Nov 29, 2009 10:29 PM in response to Cobber 99

You notice that in the second pic it is a negative temperature, super cold! I would say that the sensor is trashed. You need to contact Apple Care for warranty service. The number for your nation is in the Mac mini User Guide.

Dah•veed

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Answer 4

SimplyMac

Level 4

2,508 points

Nov 30, 2009 9:16 PM in response to Cobber 99

Since you have done the upgrades yourself to your Mini, I would just reposition the sensor.

If it continues to report too hot then possibly the sensor is bad and is in need of service.

Make sure the sensor is positioned in the proper place on the HD.

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Answer 5

Cobber 99 Author

Level 2

247 points

Dec 1, 2009 12:51 AM in response to SimplyMac

I ended up re-soldering the sensor wire back to the interconnect board. Following this and after re-positioning the sensor pad from the rear of the metal HD case to the plastic molding on the HD support, my temperature readings are back to norms, the fan is barely audible (was spinning full boar at 5,400 rpm), and mean temp has risen slightly (probably due to the fan running less). Yay! Thanks for the suggestions!

Temps at normal levels:
http://twitpic.com/rossj

Message was edited by: Cobber 99

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