For the past few months I've been doing quite a bunch of heavy load things on my Mac. So I wouldn't worry about the Fans running at full speed. Recently I've started to do more casual things. I've noticed when I turn my computer on the fan starts running at full speed. My computer's temperature is usually about 170 (150-220). The fan stills runs at full speed even when the total CPU usage 4% and with a low GPU usage. The only way I can turn my fans down is to open Macs Fan Control and set it to "auto". I have installed some fan control apps in the past but I uninstalled those. Could it be possible some leftovers are messing with my fan?

EDIT: I have removed all leftovers and the problem still continues


  • Is there any reason not to have it on Auto mode all the time ?
    – Ruskes
    Commented Mar 28, 2015 at 16:43
  • What software are you using to control the fans and read the temperature.
    – Ruskes
    Commented Mar 28, 2015 at 16:49
  • Macs Fan Control for Fan Speed and iStat menus for the temperature
    – Downgoat
    Commented Mar 28, 2015 at 17:20
  • There is no technical evidence or reason to use anything other then originally designed by Apple. = Get rid off 3d party stuff, and reset your SMC. That is unless you must tinker around with the Thermo-mechanical design of your Mac.
    – Ruskes
    Commented Mar 28, 2015 at 17:28
  • @Buscar웃 I'll try that. I installed Macs Fan Control to deal with this situation in the first place. I even have an external fan for my laptop
    – Downgoat
    Commented Mar 28, 2015 at 17:32

2 Answers 2


You mention that you use iStat Menus for temperature and a separate app for controlling the fan speed. iStat Menus has functionality to control fan speed by itself—make sure that you do not have the fan speed set to maximum in iStat Menus as this will override OS X unless another app then overrides iStat Menus.


I had my fan always on very high and couldn't find the cause. With some research I found my solution. This might only apply to me, however, I thought I share it anyway, just in case.

  • In Activity Monitor I realized that the process "launchd" uses up more than 80% of the CPU.

  • In Console "system.log" I found these lines repeating every second:

    (com.google.keystone.system.agent[79014]): Could not find and/or execute program specified by service: 2: No such file or directory: /Library/Google/GoogleSoftwareUpdate/GoogleSoftwareUpdate.bundle/Contents/Resources/GoogleSoftwareUpdateAgent.app/Contents/MacOS/GoogleSoftwareUpdateAgent

In the folder ~/Library/LaunchAgents/ I simply deleted the file com.google.keystone.agent.plist. Problem solved.

Beware! I have no clue whatsoever, what I killed there. I don't like google too much. I see no reason why google wants to update something on my machine.

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