Welcome to the SeeMeCNC Community

Using Repetier Host Mac V.56

So i've noticed on the last couple of prints, that my PLA layer fan will randomly start spinning. In Repetier I can see the fan speed slider bounce around while it's doing that. I have to click on the Fan On/OFF button to make it stop.

Can bad G-code cause the fan to start? If not, could it be that it's getting some weird interference which makes it start? I've looked to see if anything is shorting out and I can't see anything obvious. I spliced, soldered, and even put shrink wrap over the red and black wires individually to eliminate any possible shorting. Can this be a bug in Repetier perhaps?

If you see the slider bouncing around in the host software the most likely thing is bad GCode.

Good to know it's likely not a hardware issue.

So if it is a GCode issue, how would I go about disabling that fan altogether when I'm printing in ABS? What command would I be looking for in the GCode? BTW, I used the latest stable release of Slic3r to generate the code. Thanks!

I think M106 is the fan control GCode.
You might want to check your settings in the cooling tab in slicer, I don't use it, so I can't get more specific.