So i have been using matter control for a long time, and the fans come on perfecly.
Now through S3D, i set layer 1 to 0 then layer 2 to 100...
Then dont come on... am i missing something?
Try opening up the machine control panel (with the Rostock on and connected) send in an M106 S255 to make sure the fan turns on. This is to verify that the M106 is the right G-Code command to control the fan. If that checks out, then I would slice a model, export the G-Code and then open the G-Code file in a plain text editor (such as notepad for windows or textedit for mac) and make sure the M106 S255 command is in the file where you want it to be.