The 3 layer fans that cool your print (on the HE280) can be turned on manually via the LCD controller or via the host software (MatterControl). Alternatively, the fans are GCODE controlled which means your slicing program will determine the best speed and times to turn the fans on/off based on your pre-defined settings.
Here is what the GCODE for fan control looks like:
M106 - Fan On
M107 - Fan Off
Here is the manual fan control in MatterControl: