Pi 5 Fan POST Failure on Pironman 5 – "PWM Fan is not supported"

General
1

I am experiencing a persistent hardware-level fan failure on one of my Pironman 5 nodes (Raspberry Pi 5 16GB). I have multiple Pironman units in my lab, and this is the only one exhibiting this behavior despite identical software configurations.

The Problem: The CPU fan connected to the JST header fails to spin during POST. There is no initial “handshake” spin when power is first applied. Consequently, the OS fails to initialize the cooling driver.

Technical Diagnostics:

  • Kernel Status: ls /sys/class/thermal/cooling_device* returns No such file or directory. The Pi 5 firmware is not detecting the fan electrically at boot.

  • Software Logs: After a clean reinstall of the Pironman5 software (max branch), the service logs report: [ERROR] PWM Fan init failed, disable pwm_fan control.

  • Config: /boot/firmware/config.txt is confirmed with dtparam=fan=on.

  • Physical: I have reseated the 4-pin JST connector and inspected the header pins; no physical damage or bent pins are visible.

Environmental Note: The unit is booting from NVMe and has been running stable otherwise, but I cannot get the PWM controller to initialize because the fan remains dead at the hardware level.

Has anyone encountered a batch of defective fan motors or a specific firmware quirk that prevents the Pi 5 from sending the initial PWM pulse? Any advice before I proceed with a hardware RMA would be appreciated.

System Specs:

  • OS: Raspberry Pi OS (64-bit)

  • Hardware: Pi 5 16GB / Pironman 5 Case / NVMe Boot

2

Please try inserting another Pironman 5 CPU fan into this Pironman 5 to see if that fan spins. Alternatively, insert this CPU fan into another Pironman 5 to test whether the original CPU fan is defective.