Fix for constantly running fan after 10.3.8 update

Desk fan photo

©John Lillis

I got fed up with the fan that’s running constantly on my Powerbook 12″ rev b 867mhz after installing the 10.3.8 Update. So here’s how you do it:

  1. Download Update 10.2.8 and use Pacifist to extract /System/Library/ExtensionsAppleADM103x.kext from MacOSXUpdate10.2.8.pkg to the desktop.
  2. Do a backup of AppleADM103x.kext from your startup disk at /System/Library/Extensions to your home folder.
  3. Copy AppleADM103x.kext from your Desktop (the one you extracted from 10.2.8) to /System/Library/Extensions, you’ll need to enter the admin password to do that. Start Disk Utility and do a repair permissions on your start volume. Problem solved. Just for good measure, reset the parameter-RAM by holding down Command-Alt-P-R at startup. My machine now turns on the fans at 148 Fahrenheit instead of 125 Fahrenheit.

For some reason Apple choose to change the temperature when the fan starts on Rev.A Powerbook 12″ after Mac OS X 10.2.8 from 148 Fahrenheit to 125 Fahrenheit. This gives the result that the fan runs almost constantly due to the fact that the powerbook operates normally at 125 Fahrenheit. I did this hack back when Apple changed stuff in the 10.3.2 update, and they haven’t updated AppleADM103x.kext until 10.3.8.

Another thing to note is that I tried to do the Install option from Pacifist instead of the copy to the desktop. That didn’t work. My guess is that it has to do with the kextcache. maybe you just have to do a sudo kextcache -e or similar to get the kext cache to update? Haven’t tried it though.

Just a reminder, I take no responsibility if you do this hack and something goes wrong.


  1. Atle Klovning says

    Great! I’ve got the same Mac as you. I did this the previous time, and was greatly annoyed once again. I get an error message saying the ADM103 has been installed wrongly. I’ve zapped the parameter RAM as well.

    Nice web site!

  2. Jacken says

    You should check that the owner and permissions are set correctly. You also need to make sure that the kext file was correctly copied with all it’s contents (yes, it’s really a folder) and it should work.


  3. Byron says

    In order to get your temperature reading back, all you have to do is run Disk Utility and repair file permission. After it repairs, everything should work fine.

  4. bart says

    It’s quite nasty of Apple, but anyway, your trick works perfectly! I’m very happy to be fan-less again :)

  5. wayne says

    Wow, that fix of the 0.2.8 AppleADM103x.kext in my Panther did even more than fix the fan running. It actually made two more improvements. First it actually made the laptop cooler, since the fan motor isn’t heating up as much. But the most significant improvement was the greatly increased batter life (maybe 30 – 50% improvment, since i’m not wasting power by continuously running the fan. What was Apple thinking with that change? THANKS!!!!

  6. John says

    Anyway to get this working in 10.4. I’ve searched for the AppleADM10xx.kext file and I can’t find it. Any hints??

  7. Ben says

    I have the newest version of the 12″ PowerBook (1.5 Ghz) and I can’t seem to get this hack to work on my computer. Do you know of anyone who has gotten this to work on the newest (Rev. D) version of the PowerBook?

  8. says

    This is a fantastic fix and IT WORKS ! Thanks so much the fan noise has been driving me nuts.

    I have a PowerBook 867 running 10.4.11.

    Make sure you extract the file from the 10.2.8 image to your desktop as the first step or it wont work.

    Thanks again, you have made me happy :)


  9. David says

    I have tried several times, but I can’t get the fan to stop running.

    I am not sure if I got the right file. I have the MacOSXUpdate10.2.8.dmg file.

    I am not sure if I am copying the file correctly, from the desktop to the system/library/extensions folder. I am opening two windows of finder and moving the file from the desktop to the system/library/extensions folder. It tells me it can’t copy over, I press authenicate, and says it copies, then I ran disk utility and the permissions repair, restart, and I still have a fan running away like mad.

    I hope you can help me. I have a 867 15″ Powerbook G4, I love this dude, but he really noisy now. I am running. 10.4.8. 1 gig ram.

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