Yes, the Slate AX (ATX1800) got a internal fan. My Slate AX goes handwarm, nothing to worry.
There is /sys/class/thermal/thermal_zone[0-5]/ …
You can get the temp with cat /sys/class/thermal/thermal_zone[0-5]/temp and there are more files. When I remembering right one for the fan threshold …
But be aware that a wrong setting can lead to a permanent damage. Take a look at the values first, don’t expect the displayed °C are accurate. Sometimes there is a offset needed.