So for my reprap for some reason the fan will be on when I am printing some things and other times it won't turn on at all. I have gone onto slicer and set it so the fan is always on and that doesn't make a difference and I need the fan on sometimes. What could the problem be? Thank you for the help.

Try adding M106 S255 into the start Gcode in Slic3r, that should guarantee that your fan will start.

---

Through self sustaining actions comes freedom

DIY Tech Shop