Bought a new computer. Had some trouble with the fan controller built into the chassis, so got a couple of PWM fans instead since the motherboard can control 1 CPU and 3 chassis PWM fans.

The BIOS however was a bit limited when it came to how slow you could make the fan run. So turned to the fancontrol package in ubuntu, and after some fiddling it worked as intended, even turning off the case fan when the temperature was below the configured threshold.

However, after suspending then resuming, the fan would go at 100% again, and not spin down. There’s a launchpad bug that tells me I’m not the only one with this problem.

Here’s a workaround. Create /etc/pm/sleep.d/20_fancontrol with the following contents:

#!/bin/sh

case "${1}" in
    resume|thaw)
  /usr/sbin/service fancontrol restart
  ;;
esac

This will restart the fancontrol service after resume, which solves the problem. The fan will run at 100% for a little while at resume, since it takes a couple of seconds before this script is being run.