SOLVED: I replaced the leads coming from the fan motor and it is working just fine. Thanks for the input. If anyone else has this model, I would suggest printing and installing a wire clip in order to prevent the issue. Here is the one that I am using now: http://www.thingiverse.com/thing:620627

I am running a Printrbot Simple Metal with a heated bed and have not been able to get my fan to run recently. The fan used to run just fine (for the past 3 months in fact--since purchase). I cannot be certain, but this may be related to the cord getting snagged by the hot-end last week (cables have begun to sag over time). Nothing melted or damaged except for the hard-plastic coil used to bundle all cables together, and that appears to just be minor, cosmetic damage.

I have checked Cura settings, ensuring that fan operation is selected (starting at 0.6 mm) and that it is being told to run at 100%.

I have also sent 'M106 S255' from Proterface UI (this, from what I have researched, should turn the fan on at 100%). This command had no results.

The firmware is stock (Marlin), all exposed cables seem intact and without damage, and the plug to the control board seems to be fine. Maybe I could apply current to it directly and see if it runs?

EDIT1: I put 2 6V lantern batteries in series (voltmeter shows 12.3V) and hooked it to the fan cable; the fan did not budge (even with encouragement in the form of a slight push from the hand). Is there a particular spot in the cable that is vulnerable to failing if pulled on?

Any thoughts, suggestions, or things to look into?

EDIT2: I have disassembled the cable bundle leading to the fan and hot-end. I have found a connection point where the fan plugs into an extension cable which goes to the control board. I have applied current here and the fan doesn't move. I tested the current on another 12V fan laying around and that fan runs just fine. So, it seems that the fan has gone bad...somehow. I am still quite confused on how this would happen. Is it possible for a DC fan to "overheat" due to poor airflow? I have a shroud on the fan (http://d17kynu4zpq5hy.cloudfront.net/igi/printrbot/CnoDPS5D1CZ5EgBR.standard) and there has always been a little back pressure pushing wind out of the back of the fan.

EDIT3: So I have resorted to tearing into the fan and have applied 12V to the wires which are soldered directly to the fan and the fan doesn't work. I then applied the current directly to the solder points and the fan runs. Is there a reason why a set of wires, which look perfectly fine from the outside, would fail to run the fan?

  • $\begingroup$ Assuming your fan actually runs on 12V, applying power directly should make it move. Are there perhaps any other points you can try to apply power so to check if the wire is broken? $\endgroup$ Aug 30, 2016 at 20:09
  • 1
    $\begingroup$ It seems that the fan is 12V (printrbot.com/shop/fan). I have looked over the cable and cannot seem to find another point. The only thing that stands out is a random, wrapped connection point, mid cable bundle that may or may not be related to the fan. I'll investigate more. $\endgroup$
    – JG7
    Aug 30, 2016 at 20:13
  • $\begingroup$ Are this solid copper wires? Maybe you replace them by a stranded one? $\endgroup$
    – ott--
    Aug 31, 2016 at 17:58

1 Answer 1


Is there a reason why a set of wires, which look perfectly fine from the outside, would fail to run the fan?

The internal conductor is broken. This can happen over time due to metal fatigue from the constant movement, and the cables getting snagged may indeed have something to do with it. You could try desoldering the current wires from the fan and replacing them with fresh ones, or getting a new fan altogether.


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