HMS_0300_0300_0001_0001 The speed of the hotend fan is too slow or stopped
" The speed of the hot end fan is too slow or stopped. It may be stuck or damaged. "
There is a speed feedback signal from the hotend fan. the hotend fan (or called the heat break fan) is used to keep the filament outside the nozzle cool and stiff; if the hotend fan speed keeping low, then the heat beak temperature will rise and cause the filament too soft and jam inside the heatbreak.
Below are the possible reasons that this HMS error occurs:
When cleaning the fan when it's turned on, the fan may start whirling unexpectedly and cause injury. So, performing the flowing step with a pen or screwdriver is recommended as there is no switch to turn on and off the hot end fan.
Set the hot end temperature to 0°C. When the hot end temperature drops below 50°C, the hot end fan will automatically shut down (the fan turns on automatically when the hot end reaches 50°C and turns off automatically when it falls below 50°C).
Take off the front cover, and use a pen or a screwdriver to spin the fan blade, to see if the fan blade was stuck by something. If yes, please remove it.
After cleaning up the mess, reconnect the 4-PIN connector on the hot end fan. Set the hot end temperature to 51°C. The hot end fan will start running again (if it is not stuck or broken) and see if this HMS message disappears.
If have a P1P printer, please be careful not to plug the hot end fan in the wrong way.
If you still can't solve this problem. It is recommended that you re-plug the 10-pin connector. And check whether there is any sign of damage on the 10-pin plug.
If the error still exists after re-plugging the two connectors multiple times, please take photos of the plug of the 10-pin connector and the hot end fan, upload log files, and contact the customer support team.
If your X1 series printer has a V9 TH board, please replug both ends of this FPC. (Because the BTB socket is small, the installation of the FPC is a bit tricky. It is recommended that you only plug and unplug one end at a time and do not press too hard.)
If your printer model is P1P, please replug both ends of this FPC.
If you have a spare hot-end fan or a complete hot-end assembly (with the fan), you can replace it with a new fan to see if it can fix the problem. Replacing the hotend/ceramic heater/thermistor/cooling fan | Bambu Lab Wiki
If the problem cannot be solved through the above steps, it is likely that the TH board is faulty. Please contact after-sales service for replacement.