The machine will print fine for about 15 minutes before the temps begin to fall and the machine will pause. Hitting resume and the temp will just struggle to rise above 180-200 until it gives up and pauses again.
Everything is fine for the first ~15 minutes of use.
I have changed the hotend/thermistor/heater and ran calibration, it still does the exact same thing.
I also noticed my hotend fan is on all the time as soon as you power on the printer and never turns off.
What should I check next?
this hasnt happened on any bambulab to me, but in my old printers if the nozzle was blocked (partially, like the ptfe tube degraded) it was failing like this. Have you checked that there is no obstruction?
first things I would test:
run a print with a way lower volumetric flow limit, like 4, see if it runs longer / shorter.
If you set the temp manually with the machine idle (keeping an eye on it and dont let it idle the temp lower as its designed to do) what happens
and lastly raise a support ticket, you’ll be able to send logs to bambu (would be nice to just view them ourselves) it might be the tool board starting to fail
and maybe try reseating the ribbon cable (both ends) that connects the front board to the back one
After a failure and a power cycle, if you start another print immediately does it fail the same way, or faster?
The hotend fan starting up immediately makes me think temp is being miss reported or the board starting to fail is causing juice to run to the fan constantly, the hotend electronics becoming heat soaked might be the trigger for the heater to lose power