Bambu Lab AMS HT — Problems and fixes

Common problems with the Bambu Lab AMS HT and what to do about them. If filament will not feed in or come out, do not force it.

What you may fix yourself

You may follow Bambu Lab's official troubleshooting guides, as long as the fix needs no screws removed and no wires disconnected. If it does, post in Slack and wait for a room developer or board member to reply before you start. Taking a PTFE tube off is fine when the official guide says so, as long as you put it back exactly as it was, pushed all the way in. Changing how filament is fed is never a fix.

The status light and common problems

What you see	Likely cause	What to do
A pause before a filament change, with a fan running	The AMS HT is cooling its chamber before it feeds filament that would soften	Normal. Wait.
Water droplets inside	The spool was far too wet	Open the lid briefly to let the steam out. Dry the spool in a dryer before using it again.
White light flashing about every 3 seconds	The AMS HT is starting up	Normal. Wait.
White light steady	Filament is in the slot and the unit is ready, or it is loading, reading the RFID tag or printing	Normal.
White light off	Nothing has happened for a while, and the light has gone to sleep	Normal.
White light slowly fading in and out	Drying	Normal.
Red light flashing twice	The printer can't see the AMS HT, or a feed or unload failed	Check that the AMS HT shows on the printer screen and that the lid is closed and locked. If it doesn't clear, report it in Slack.
Red light slowly fading in and out	No filament was detected after the print started, or a fault in the drying system	If the spool has run out or the filament isn't in, insert it and the light goes back to normal. Otherwise, report it in Slack.
Red light steady	Filament has probably broken off inside the unit, near the outlet	Do not force it. Fixing it means taking the unit apart, so report it in Slack.
Red light single flash	Feed failure: the feeder may be caught in debris, or the tube inside is clogged	Do not force it. Fixing it means taking the unit apart, so report it in Slack.
"Filament broken in path" on the printer screen, and the AMS HT light is not steady red	Damp filament that has gone brittle and snapped, in the tube between the AMS HT and the printer	Follow Bambu's guide for this fault. (A steady red light means it broke inside the unit: see the row above.) If it has you take the PTFE tube off to pull the piece out, that is fine, but put the tube back as it was. If the piece is further in than the guide covers, ask in Slack. Dry your filament before using it again.
Loading feels stiff, or a tube looks damaged	Worn PTFE tubes	Report it in Slack. Replacing a tube needs spare parts, so it is coordinated there first.
The spool won't lift out	The filament is still in the printer	Run Unload on the screen.
The right nozzle's part looks rougher, or the print is slow	The right nozzle's Bowden drive is slower and less precise than the left nozzle	Normal. Use the left nozzle where finish matters.