A1 series printers are equipped with the nozzle clumping detection function, you can refer to the wiki for details: Nozzle clumping detection | Bambu Lab Wiki
The extrusion force sensor is used to detect whether the nozzle is wrapped by filament, if the nozzle is wrapped by filament, or if the build plate is placed incorrectly, the force on the nozzle will change. When the nozzle clumping detection is enabled, the nozzle will move outside the heat bed and then continue to move down. If the nozzle is wrapped by the filament, forming a thick material mass, the process of the above movement will cause the material mass to hit the heat bed and cause the force change. The change in force will be detected by the extrusion force sensor (eddy current sensor coil).
The detection process is shown as follows:
HMS_0300_1A00_0002_0001 The nozzle is wrapped in the filament or the build plate is placed incorrectly.
0300-1A00-0002-0001