I have ASUS FX504GD having ubuntu 18.04.1 and kernel 4.20 .
For some reason I am not able to find fan drivers for ubuntu. This laptop has a dual fan.
I tried installing asus_fan from https://wiki.archlinux.org/index.php/fan_speed_control#Asus_laptops but having no luck since this module works only for the older Asus laptops.
This is the output I get after running sensors command
asus-isa-0000
Adapter: ISA adapter
cpu_fan: -1 RPM
coretemp-isa-0000
Adapter: ISA adapter
Package id 0: +59.0°C (high = +100.0°C, crit = +100.0°C)
Core 0: +59.0°C (high = +100.0°C, crit = +100.0°C)
Core 1: +59.0°C (high = +100.0°C, crit = +100.0°C)
Core 2: +55.0°C (high = +100.0°C, crit = +100.0°C)
Core 3: +56.0°C (high = +100.0°C, crit = +100.0°C)