H2D: Part Cooling Fan running at 100% all the time, feels excessive?

Bambu Lab H2 Series
1

I recently got an H2D (only a few days old) and I’m noticing something that feels wrong with the part cooling fan.

My part cooling fan is running at 100% speed constantly from start to finish. It doesn’t seem to ramp up or down based on the layer time or overhangs—it just stays pinned at max. This happens with both PLA and PETG using the standard/generic profiles. I’ve tested with generic PLA and Bambu PLA, no difference.

  1. It’s incredibly loud.
  2. Print quality issues: My prints are looking “dry”, which I’ve read can mean they are being cooled too hard.
  3. Confirmed by others: I posted about this on Reddit and another user confirmed their H2D is doing the exact same thing (stuck at 100%). Interestingly, they also have an A1 which manages the fan speeds normally/quietly, so the issue seems specific to the H2D logic. But it also seems to be confirmed by other users with other machines so who knows where the problem actually lies.

What I’ve checked:

  • Firmware is fully updated.
  • I’m using the default built-in presets in Bambu Studio (no custom G-code).
  • Happens on my own sliced files and pre-sliced MakerWorld models.

Has anyone else with an H2 series noticed this? I’d prefer the printer to manage fan speeds automatically based on the filament settings rather than just blasting 100% air all the time.

Thanks!

2

try reboot the printer? if it doesn’t fix your problem then it’s time to submit support ticket.

3

Thanks for the tip!

I will post a support ticket too and see if the issue is resolved that way. I’ll also update this post with any additional information I may receive to help others with the same issue! :slight_smile:

4

also check if the sound you’re hearing is actually part cooling fan. It could be the chamber ventilation fan too

5

I thought it was something else until I manually turned off all the other fans in the chamber during a print to test. It’s definitely the part cooling fan

6

If you are certain that the part cooling fan is running at 100%, this may be the cause:

On the H2D, it is completely normal for the part cooling fan to ramp up towards 100% with PLA/PETG when layers are very fast or small – the slicer’s auto-cooling logic controls the fan based on layer time. The filament profile has a min/max fan curve linked to “minimum layer time”: at short layer times, the fan is pushed towards maximum; at longer layer times, it stays closer to the minimum value.

For PLA, 100% is often acceptable, but for PETG you should limit the maximum part cooling fan (e.g., around 50–60%) or allow the printer to slow down rather than over-cooling small features.

1 Like
7

Thanks for your reply.

I did some digging and double checked my settings for different filaments. Bambu has more faith in their own filaments that generic ones it seems (makes sense) so the standard setting for their own filaments follows a min/max curve as you also talk about while the generic filaments are set to 100% fan speed no matter what. I think that this here is the key to my issues. I spent some time looking at the fan speeds while running a few different prints and they are indeed not 100% all the time with Bambu filaments.

8

That’s certainly the case. They know the limits of their own filaments but obviously can’t account for what generic filament you might be using.

Glad the answer was helpful! :slight_smile:

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