Mac Mini, fan started running full speed tonight?

Discussion in 'Mac mini' started by PaulexPC, May 26, 2010.

  1. PaulexPC macrumors member

    Jun 4, 2008
    I have a one year old Mac Mini.
    Just this evening when I turned it on the fan is running at full speed, and quite loud. I turned it off an rebooted, still full speed fan.

    Oh crap. I think my warranty expired about a month ago.
    What could be wrong with it?

    Also the front LED is off. I have not opened this unit up since a year ago when my friend and I installed new RAM (the machine was brand new at the time)
  2. Genl. Ludd macrumors newbie

    Mar 15, 2009
    Check for runaway processor

    Hi: I had that problem, and found that a processor was taking up 94% of CPU processing.

    I found out through the iSTAT widget on the dashboard. It showed a processor with the name starting with AV.

    You can go to the Utility > Activity Monitor

    Click on the %CPU and see if one is taking up a high percentage.

    You can select that process and click Quit Process. When i did it things went back to normal and the fan quieted. It lasted through a restart.

    If the user is "root" you might have to be very cautious. You can try it, but it may bomb the system and you will have to restart, but at least you will know it probably isn't your hardware.
  3. billib macrumors member


    Apr 23, 2009

    Hi, I don't know about the LED not working but for your processor
    problem, launch your "Activity Monitor" located in your Utilities folder.
    In its Menu Bar choose "All Processes" in the Drop Down Menu.
    Then scroll down to expose "ptmd". Quit it!!!!!!! That should stop
    your processor from being hammered and your temperature should
    drop back down to something reasonable. Its a known bug. One of
    Apples updates should eventually fix it. BTW, I have this problem
    on a First Gen. Intel mini.
  4. tchyfeeley macrumors newbie

    Jun 12, 2010
    Mac Mini full speed fan even when off

    My Mac mini started the same thing....although, my fan runs at full speed even when it's off. Just plug in the AC power cord and it sounds like a jet engine. This makes me believe that the problem is hardware related....anyone have any ideas?
  5. billib macrumors member


    Apr 23, 2009
    Temp. Sensor

    People who have detached their temperature sensor from their processor
    and not reattach it cause the fan to run full speed with the mini plugged in
    and powered up. Sorry. I can't help you with your problem. It sounds like
    your Mother Board maybe going bad.
  6. Sun Baked macrumors G5

    Sun Baked

    May 19, 2002
    Get the system restore disc #1 and restart holding down the D key, and run the Apple Hardware Test.

    Likely it'll show a 4sns error, which is probably a sensor error.
  7. jlg89, Jun 26, 2014
    Last edited: Jun 27, 2014

    jlg89 macrumors newbie

    Jan 8, 2011
    I also have a late 2009 mini with a fan that comes on full blast as soon as the power cable is plugged in. Apple's diagnostics will tell you it's a bad fan, but given that it's happening before you even hit the power button, that's probably not the issue (I tested mine with a known-good fan, and it did the same thing). My best guess is that the chip that regulates the voltage going to fan is fried, so instead of a variable voltage the fan is getting a full-on 18VDC.

    You can measure this by opening the mini, and putting a voltmeter across the black and grey wires on the fan connector--as you're looking at the rear of the mini, with the cover off, the fan connector is near the middle of the small circuit board that hangs at the rear of the optical drive. It's the 3-wire connector with black, blue, and grey wires.

    Fan control software won't fix this, because (if I'm right) the chip that the software needs to control is fried. The only "right" way to fix this is with a new logic board. That's not acceptable to me, so I went online and bought a 10 Watt, 220 Ohm resistor, cut the black wire, and put the resistor inline. That drops the fan speed to ~2600 RPM, which is slow enough to be reasonably quiet but fast enough to keep the mini cool under most circumstances.

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