Fan behavior differences between Ubuntu Server 24.04 LTS and Debian Bookworm

[kmanwar89]

I have a Raspberry Pi 4 and the ArgonONE V2 case, which I absolutely love. When I had Debian Bookworm installed on the Pi, after running the script from the ArgoneONE official GitHub repo, the fans would reduce to a near-silent speed (I'd estimate <10%)

Installing Ubuntu Server 24.04 LTS on the exact same Pi, with the exact same script, yields the fan running at a reduced, still audible, speed - I don't have a great way to measure it, and the script does not provide the actual fan speed:

--------------------------
 Argon System Information
--------------------------

  1. Temperatures
  2. CPU Utilization
  3. Storage Capacity
  4. RAM
  5. IP Address
  6. Fan Speed

  0. Cancel
Enter Number (0-6):6
--------------------------
TEMPERATURE INFORMATION:
   CPU: 36.5°C
FAN CONFIGURATION INFORMATION:
        65.0=100
        60.0=80
        55.0=60
FAN SPEED INFORMATION:
   Fan Speed 0

As seen in the above output, the temperatures are nearly 20 degrees under the 55 degree threshold, so I would not expect the fan to need to run at all.

Is there an OS-level difference that needs to be investigated here? Ubuntu is based on Debian, so I would expect the behavior to be the same across both. There is no difference in behavior even after a reboot.