Acer Aspire One fan control for FreeBSD
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ACERHDF(4) FreeBSD Kernel Interfaces Manual ACERHDF(4)


acerhdf — Acer Aspire One fan control


The acerhdf driver allows you to control the fans of some of the Acer Aspire One netbook models, so that they are not constantly running. Other netbooks might be supported as well. See SUPPORTED DEVICES for more details. It is a port of the Linux kernel module with the same name.

acerhdf monitors the system temperature and turns the fan on if it is above the fan-on threshold, and turns it off again if the temperature drops below the fan-off threshold.


Set to 1 if acerhdf should start controlling the fan. Defaults to 0, which means acerhdf is not in control of the fan.
The temperature at which the fan should be turned on. Defaults to 60.
The temperature at which the fan should be turned off again. Defaults to 53.
Read-only. Returns the current fan state, auto if the fan is running or off.
Seconds to wait between temperature polls. Defaults to 5 seconds.
Read-only. The current system temperature in degree Celsius.


acerhdf was tested on an Acer Aspire One A150 running FreeBSD 12.0 only. The FreeBSD port will most likely support the same range of devices as the original Linux version. This is entirely untested however.

Acer AO521
Acer AO531h
Acer AO751h
Acer Aspire 1410
Acer Aspire 1810T
Acer Aspire 1810TZ
Acer Aspire 1825PTZ
Acer Aspire 5315
Acer Aspire 5739G
Acer Aspire 5755G
Acer Aspire One 753
Acer Aspire One A110
Acer Aspire One A150
Acer Extensa 5420
Acer LT-10Q
Acer TM8573T
Acer TravelMate 7730G
Gateway AOA110
Gateway AOA150
Gateway LT31
Packard Bell AOA110
Packard Bell AOA150
Packard Bell DOA150
Packard Bell DOTMA
Packard Bell DOTMU
Packard Bell DOTVR46
Packard Bell ENBFT


To enable acerhdf make sure it is installed in /boot/modules and add the following settings to your /boot/loader.conf:


and your /etc/sysctl.conf:


You may want to adjust the fan-on and fan-off thresholds as well.


The system needs to have a hard drive installed, otherwise acerhdf will not work correctly and the system will automatically power down after some time. This behavior is enforced by the BIOS and there is no known workaround. This bug is present in the Linux version as well.


acerhdf was ported from Linux to FreeBSD by Tobias Kortkamp <>.

The original Linux version of this module was written by: Peter Feuerer <> and Borislav Petkov <>.

August 26, 2016 FreeBSD 10.3