1. Install the necessary package

$sudo apt install thinkfan lm-sensors

2. Create the configuration file

$sudo nano /etc/thinkfan.conf

add this lines:

sensors:
- tpacpi: /proc/acpi/ibm/thermal
indices: [0]

fans:
- tpacpi: /proc/acpi/ibm/fan

levels:
- [0, 0, 55]
- [1, 54, 56]
- [2, 55, 60]
- [3, 59, 62]
- [4, 60, 67]
- [5, 64, 74]
- [6, 70, 83]
- [7, 78, 96]
- [127, 89, 32767]

look at https://wiki.gentoo.org/wiki/Fan_speed_control/thinkfan

! levels : [speed level | start temp | end temp]

3. Enable acpi_fancontrol

$sudo nano /etc/modprobe.d/thinkpad_acpi.conf

add this lines:

options thinkpad_acpi fan_control=1

Activate kernel settings by running this:

$sudo modprobe -r thinkpad_acpi && sudo modprobe thinkpad_acpi

4. Enable the thinkfan.service

4a. runit

$sudo mkdir /etc/sv/thinkfan

$sudo mkdir /etc/sv/thinkfan/log

$sudo nano /etc/sv/thinkfan/run

#!/bin/sh

[ -r ./conf ] && . ./conf

exec thinkfan -n ${OPTS:-} 2>&1

$ sudo chmod +x /etc/sv/thinkfan/run

$sudo nano /etc/sv/thinkfan/conf

# -- mode: sh; --

# Additional command line arguments for thinkfan(1)
OPTS=''

# Setting this to 1 enables logging, any other value - disables.
LOGGING_ENABLE=1
# The directory will be created for you, if logging is enabled.
LOG_DIR='/var/log/thinkfan'

$sudo nano /etc/sv/thinkfan/log/run

#!/bin/sh

[ -r ../conf ] && . ../conf

if [ "${LOGGING_ENABLE}x" = "1x" ]; then
# Create the log directory if not exists.
[ -d "${LOG_DIR}" ] || mkdir -p "${LOG_DIR}"

exec svlogd -tt "${LOG_DIR}"
else
exec chpst -b thinkfan-log-null cat >/dev/null
fi

$ sudo chmod +x /etc/sv/thinkfan/log/run

$sudo ln -s /etc/sv/thinkfan /etc/runit/runsvdir/default

4b. systemd

In order to start the service any time you boot up your machine, we need to enable it!

$sudo systemctl enable --now thinkfan.service

5. Check if the service is running !

5a. runit

$sudo sv status thinkfan

5b. systemd

$sudo systemctl status thinkfan.service

This never worked for me: https://web.archive.org/web/20220711225154if_/https://askubuntu.com/questions/22108/how-to-control-fan-speed/1139409#1139409