[Bug] H2S exhaust fan reporting/setting

[TXJustin]

Home Assistant Version

2026.3.2

Bambu Lab Integration Version

2.2.21

Describe the bug

On the H2S (can't speak for other H2 variants) if you set the chamber fan speed manually, home assistant logs it switching values back and forth from the value set and 10% slower every 5 seconds. This is true if you set the value from Home Assistant, and also true if you set the speed from Bambu Studio. When the printer itself sets the speed, the issue does not occur.

To Reproduce

1. Within Home Assistant from the Print Status card, set the chamber fan speed to, for example 60%.
2. Check Activity within Home Assistant

• or -

1. Within Bambu Studio on the Device tab, click Air Condition and pick a value for exhaust fan, for example 20%
2. Within Home Assistant check Activity

Expected Behaviour

Consistent number

What device are you using?

A1

Diagnostic Output

No response

Log Extracts

No response

Other Information

No response

[AdrianGarside]

Seems like that's a firmware bug since the integration just reports what the printer puts in the mqtt payload.

[TXJustin]

OK. I wasn't sure if that was the case or it was something about how ... I don't know what to call it ... how HA will use numbers from 0-255 for fans and lights and how that "converts" to a percentage.

I think the behavior is a non-issue for most people. The printer is in my office and this room often manages to be at the magic temperature when printing PLA that the printer will detect the chamber too cool, close the top vent then a second later detect the chamber too warm, and open the top vent and this may happen 20 times in a row because Bambu has no "float", so I have an automation that detects this and sets the fan manually to 20% - the chamber will get to 1c lower than Bambu would like but it doesn't effect the print but is kinder on the printer and my sanity and so once that happens a 6 hour print means 21k log entries

I found time_throttle that can be set in the configuratino.yaml for a sensor, so thinking I might try that set to 60 seconds but then I don't think it will capture being set to 0 when a print ends and I may need to use an automation to set that. Curious if you have any different/better suggestions, or see other issues with using the throttle that I'm not considering ?