for one, v24 is available, you can install that right from glinet,
I'm guessing you got it directly from openwrt?
As far as controlling the fan goes, I tested this with v24 openwrt from glinet,
you can test settings with:
/etc/init.d/gl_fan stop
gl_fan -v -t 45 -i 4 -d 20
otherwise set it persistently across reboot;
uci set glfan.@globals[0].temperature='45' #target temp in c
uci set glfan.@globals[0].integration='4' #fan ramping
uci set glfan.@globals[0].differential='20' #polling time in seconds
uci commit glfan
/etc/init.d/gl_fan restart
use a temp higher than 45 if you dont want it constantly running around 2500rpm