Zero-configuration fan control daemon for ThinkPads.

• Extremely small (~430 lines), simple, and easy to understand code
• Sensible out of the box, configuration is optional (see "usage" below)
• Strong focus on stopping the fan as soon as safe to do so, without inducing throttling
• Automatic temperature- and time-based hysteresis: no bouncing between fan levels
• Watchdog support
• Minimal resource usage

zcfan has the following default fan states:

If no trip temperature is reached, the fan will be turned off.

The fan will also only be reduced once the temperature is now at least 10C below the trip temperature for the current fan state. This can be tuned with the config parameter temp_hysteresis.

To override these defaults, you can override the file at /etc/zcfan.conf with updated trip temperatures in degrees celsius and/or fan levels. As an example:

max_temp 90
med_2_temp 80
med_1_temp 70
low_temp 55
temp_hysteresis 20

max_level full-speed
med_2_level 7
med_1_level 4
low_level 1

We will only reduce the fan level again once:

1. The temperature is now at least temp_hysteresis Celsius (default 10C) below the trip point, and
2. At least 3 seconds have elapsed since the initial trip.

This avoids unnecessary fluctuations in fan speed.

I wrote zcfan because I found thinkfan's configuration and code complexity too much for my tastes. Use whichever suits your needs.

Run make.

Requires gcc and make

1. Compile zcfan or install from the AUR package
2. Load your thinkpad_acpi module with fan_control=1
   • At runtime: rmmod thinkpad_acpi && modprobe thinkpad_acpi fan_control=1
   • By default: echo options thinkpad_acpi fan_control=1 > /etc/modprobe.d/99-fancontrol.conf
3. Run zcfan as root (or use the zcfan systemd service provided)
4. If you run a laptop which keeps the fan running during suspend, you will also want to send SIGPWR before sleep and SIGUSR2 before wakeup to avoid that. For systemd users, enable the zcfan-sleep.service and zcfan-resume.service units to do that automatically.

While the author uses this on their own machine, obviously there is no warranty whatsoever.