Larkbox Fan - Which sensor/register to tell if on?

Hello Everyone,

Does anyone know which sensor or register can be read to determine if the Larkbox fan is on or off? I am monitoring the temperatures on my Larkbox and I would like to add a sensor for fan on/off. However, of the lists of sensor available in HWinfo does not list any for the fan.

PS. So far, my Larkbox has been performing very well and I have not had any issues. Thank you to my lucky stars.

Thanks for the help

my gues, bcz fan go up with temperature above 54degree, if you have that temperature, the fan will be always on