Clear all

Part cooling fan not spinning during print  

Active Member
Part cooling fan not spinning during print


I performed the MK2S -> MK2.5S upgrade and I am having huge quality issues (especially since my MK2S had always given me nothing but perfect quality).

I rapidly noticed that the cause of the issue appears to be that the fan cooling part is not turning during print.

I tried:

- Adjusting part cooling fan speed from 255 to 0 and back to 255 from the 'tune' menu. Still the fan would not turn

- Checking Prusa Slicer setting: the fan is indeed supposed to be turned on after the first layer

- Running the self-diagnostic function from the printer menu: the fan is spinning!

I observe that the self-diagnostic tool brings the extruder to the far left of the printing bed while I print in the middle of it. Do you think it might be possible that the fan cable could be defective and breaks in some positions but not while the extruder is on the left?

Is there a way to turn on the fan manually and then haver the X axis move to check whether the position has an influence on the fan spinning or not?

Or could this be a firmware issue?

Any help appreciated, thank you in advance.



Publié : 25/04/2020 2:39 pm
Active Member
Topic starter answered:
RE: Part cooling fan not spinning during print

OK, so responding to myself. 

I found a way to check my theory: in the settings/temperature menu, there is a fan speed value that can be changed even when the printer is not running. 

I set it to 255 and, with the motor disabled, moved the extruder along the x axis. 

As I suspected, the fan turns on the first 1/3rd of the x axis from the left and then it stops turning. When I return it to the left, the fan starts spinning again.

I have to say that this was the part I was most fearful about the upgrade: the wires have flexed for hundreds of hours in one direction and the complete dismantling of the electrical bundle meant that the cables would not be positioned the same way. They now flex in a different direction and break due to the metal fatigue.

I will have to replace the fan cable but I hope that it will not trigger another cable to fail if I rewrap the electrical bundle in yet another position.,,


Publié : 25/04/2020 4:01 pm
Partager :