# Cooling tower fan not getting detected

**URL:** <https://forum.sunfounder.com/t/cooling-tower-fan-not-getting-detected/4606>\
**Category:** General\
**Created:** [May 2, 2026, 4:17am UTC](https://forum.sunfounder.com/t/cooling-tower-fan-not-getting-detected/4606 "2026-05-02T04:17:00Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![cnarun1984](https://avatars.discourse-cdn.com/v4/letter/c/c37758/32.png) [@cnarun1984](https://forum.sunfounder.com/u/cnarun1984)\
**Post date:** [May 2, 2026, 4:17am UTC](https://forum.sunfounder.com/t/cooling-tower-fan-not-getting-detected/4606/1 "2026-05-02T04:17:00Z")

</div>

Hi,

I’m facing an issue with the **CPU tower cooler fan** on my Pironman 5 setup.

### Setup

- Raspberry Pi 5

- Pironman 5 case (using the provided 4-pin PWM CPU fan)

- Raspberry Pi OS (tested on both NVMe and microSD)

### Issue

- The CPU fan **spins briefly at boot**

- After the system fully boots, the fan **stops and never spins again** , even under load

- CPU temperature crosses **50°C+** , but the fan still does not start

### What I’ve tested

- Reinstalled Raspberry Pi OS (both SD and NVMe)

- Tested **without Pironman software installed**

- Reseated the fan connector multiple times

- Confirmed the fan is connected to the **Pi 5 4-pin fan header**

### Diagnostic output

```auto
ls /sys/class/thermal/

```

Output:

```auto
thermal_zone0

```

👉 There is **no `cooling_device0`** , which suggests the fan is not being detected by the system.

I also tried:

```auto
cat /sys/class/thermal/cooling_device0/cur_state

```

Result:

```auto
No such file or directory

```

### Observation

- Fan gets power at boot (spins briefly)

- But appears **not detected as a PWM fan by the OS**

* * *

### Question

- Is this a known issue with the Pironman 5 CPU fan?

- Could this be a **cable / pinout / compatibility issue** with the Pi 5 fan header?

- Is there any additional driver or configuration required for the CPU fan (not the RGB fans)?

* * *

Any guidance would be appreciated.

---

<div class="post-metadata">

**Author:** ![SunFounder\_Moderator](https://avatars.discourse-cdn.com/v4/letter/s/34f0e0/32.png) [@SunFounder\_Moderator](https://forum.sunfounder.com/u/SunFounder_Moderator)\
**Post date:** [May 6, 2026, 8:28am UTC](https://forum.sunfounder.com/t/cooling-tower-fan-not-getting-detected/4606/2 "2026-05-06T08:28:45Z")

</div>

The cooling tower is directly controlled by the Raspberry Pi’s fan control strategy. You can run the following commands to check whether the fan is working:

Keep the fan running at full speed  
pinctrl FAN\_PWM op dl

Stop the fan completely  
pinctrl FAN\_PWM op dh

Let the fan follow the Raspberry Pi’s default fan control strategy (typically starts at around 50°C)  
pinctrl FAN\_PWM a0

Please run these three commands to see if the fan responds properly. If it works as expected, you can simply leave it with pinctrl FAN\_PWM a0.

By the way, may I ask — were these fan testing commands provided by an AI? Recently, I’ve noticed many people using incorrect commands when testing Raspberry Pi fans with the help of AI.