Issue type: Equipment Problem
Area: 3D Printing
Equipment: Prusa MK3S+ - Sunwukong
Summary: Print paused with fan error
Additional Info: Print resumed just fine, but temperature seems intermittently off
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Fan error encountered:
Print resumed and completed without issue. However, the fan duct appears to be bent/melted/recently crashed:
In addition, while watching the rest of the print I noticed that temperature was varying more widely than I expected. I was printing PETG at 255C, would see gradual drops towards 250, occasional drops to 245 (can vary with flow rate), then very sudden spikes to 265, holding above 260 for a while.
I think we should rerun PID tuning next volunteer day, and check thermistor functionality as well.
I hesitate to recommend the newer firmware with thermal modeling included - mine at home occasionally complains at >12mm/s^3 even after tuning. So I don’t think it’s great for unattended printing.
It also may be a failure somewhere between the board and fan, I’d suspect either a wire failing in the cable chain or a crimp/solder issue at one of the ends in this case.
I’m basing this mostly off of Err: PRINT FAN ERROR | Prusa Knowledge Base that claims this specific error is a result of not getting tachometer information from the print cooling fan. Checking the thermistor and rerunning PID tuning are both good to do as well, I’m not certain if this error code is used for other related failures.
Either the power or ground wire failing would cause the fan to occasionally stop spinning, which would make the tachometer gradually read zero, or it could be the yellow tachometer wire itself failing and reporting zero despite the fan spinning. There’s a fan RPM display in Support > Extruder info, moving the extruder around slowly while also bending the cable chain around might result in dropping RPMs (more likely to be power or ground wire), or sudden drops to zero (likely to be the yellow tachometer wire).
@flowmage, this is the fan duct that you replaced at the work day today, right?
Yes, I replaced the broken fan duct. There was no evidence of any fan errors during testing it calibration. I think we can call this one closed!
Someone has finished work on this and called it done.
Thank you for reporting it and helping us keep track of what needs attention.
