Hot End Fan Not Running Error
I have just under 500 hours of print time on my Core One. Recently I started a 12hr print with some PLA and went to bed. Woke up in the morning to the printer beeping and flashing an error of "Hot End Fan Not Running" with a QR code for diagnosing. I cleared the failed print off the bed and started digging in. I ran all the fan tests, and it continues to fail for the same reason. But the odd thing is the fan runs. In fact, it seems to run exactly the same as it did before the issue started. I've removed the fan from the unit and cleaned it out with compressed air. I didn't find anything that I would consider cause for alarm. I reinstalled, checked all wiring, checked the plug, fan seems to function, but test still fails and gives the "hot end fan not running" error continuously. I'm kind of at a loss at what to do now. I guess I should probably just replace the fan.
Youtube short of the test and fan running: https://youtube.com/shorts/_F7mH0vQphs?si=9fUEtiaLKlj3Kls6
Any other suggestions? I've reached out to Prusa via email and haven't heard anything back yet.
RE: Hot End Fan Not Running Error
There might be a bit more to it for example, maybe the fan is unable to reach the required number of RPM's? Regardless, I would contact Prusa support over chat. Email can take awhile. Is your Core One factory assembled, a kit or an MK4S upgrade kit? It's possible they can send you a new fan if it's under warranty.
RE:
Purchased as a factory assembled unit (shorter lead time when I ordered). Yeah, I figured it's something like that. The PLA I was running at the time seemed a little "stringy" so I thought for sure I would find debris in the fan, but it was surprisingly clean. No noticeable drag etc. I will reach out to chat. I may just order a new fan in the meantime since it's inexpensive and it seems like the quicker fix to get up and running again.
'Fan not running' means the controller is getting no feedback from the fan, it is not seeing (any) pulses at the correct speed - the commonest causes are, in order of easiest to check:
Dirty fan blades, fine stringing tangles around the fan hub, a bad, possibly dirty connection - re-seat and maybe clean the plug(s), a dry bearing - a tiny drop of light oil in the fan hub used to fix a lot of Mk3 issues - and possibly a broken conductor in the connecting wire.
Cheerio,
RE:
Further to this, I wish Prusa would enhance the firmware to display which test case failed. Not just "Fan Test X" but allow me to perhaps select it and get a report on the screen: "Fan not able to reach 1234 rpm's check ABC" etc
RE: Hot End Fan Not Running Error
Prusa emailed me back and was nice enough to send me some troubleshooting tips which I will share here because they seem incredibly useful. Aside from that I did reach out to chat yesterday before my email response and they are sending me a new fan. I should have it before the end of the week, according to them.
Here's the troubleshooting tips:
