Raspberry Pi 5 Active Cooler Not Spinning: 30 Threads Sorted
I do not own a Raspberry Pi 5. This blog runs on a Mac mini, and every Pi 5 post here says so in the first line. What I have is a search log: off the seed “raspberry pi 5 active cooler”, Google returns 142 completions, and the ones about the fan misbehaving (“not working” 14, “not spinning” 10, “fan not spinning” 10, “not running” 4, “how to enable” 4) add up to more than the ones about installing it. So this is a desk job. I read the product brief, the overlay README that defines the fan curve, the bootloader release notes, and 30 threads and issues in which someone’s cooler either sat still or ran flat out, and sorted each by what it turned out to be. Half of the “broken” coolers were doing exactly what the firmware told them to.
The fan is supposed to be off most of the time
The Active Cooler is a blower on an anodised aluminium heatsink, clipped to the board with two push pins and plugged into the four-pin header marked FAN. The product brief (January 2026 revision) rates it at 8000 RPM ±15 % and 1.09 CFM maximum, with PWM control and a tachometer line, and promises production until at least January 2036. What the brief does not print is the curve, which lives in the overlays README in the firmware repo as four fan_temp parameters, Pi 5 only:
| Step | Turns on at | Turns off below | PWM (0–255) | Duty |
|---|---|---|---|---|
| 0 | 50 °C | 45 °C | 75 | 29 % |
| 1 | 60 °C | 55 °C | 125 | 49 % |
| 2 | 67.5 °C | 62.5 °C | 175 | 69 % |
| 3 | 75 °C | 70 °C | 250 | 98 % |
Two things follow. Below 50 °C the fan does not turn, and once it is on it stays on until the SoC is five degrees under the step that started it. A Raspberry Pi engineer spelled this out in October 2023 to a user who thought the fan was misbehaving in the forties: “there’s an extra threshold of 50C where the fan turns on essentially silently … each of the thresholds except the critical shutdown has a hysteresis of 5C” (PhilE, forum thread 358257). The other thing every owner notices is a one-second burst at full speed on power-up. That is the firmware probing for a fan, and it cannot be switched off. When a user asked in June 2024 how to silence it, the answer was “That is the fan detection routine. It is under control of the firmware” (rpdom, thread 372685). The probe, per the engineer who maintains the bootloader, “works by driving the fan-PWM low (max-speed) and observing fan-tach” (timg236, rpi-eeprom #660). Keep that sentence in mind; most of the hard failures below are that probe not seeing a tachometer.
30 threads, sorted by what was actually wrong
The set is 18 threads on forums.raspberrypi.com found through search results for the fan not spinning or running at full speed, one DietPi forum thread, one Ubuntu Launchpad bug, one Talos issue, and nine issues across the rpi-eeprom, linux, firmware and documentation repos, dated October 2023 to August 2026. Reddit was not reachable from this machine and is not counted. I sorted each by the cause the thread settled on, not by the title.
| Symptom | Cause the thread settled on | Count | What fixed it |
|---|---|---|---|
| Never spins, or stops after the boot burst | Working as designed (below 50 °C, or hysteresis) | 4 | Nothing; load the CPU and watch it start |
| Bent tachometer pin in the FAN header | 1 | Straightened with tweezers | |
| Dead or worn fan | 2 | Replacement fan | |
| Kernel without the RP1 PWM driver | 2 | Pi kernel, or a userspace hack | |
| USB rail switched off, or an odd USB boot adapter | 2 | Re-enable USB; swap adapter | |
| Cannot be disabled (boot probe) | 2 | Not a fault | |
| Runs at 100 % all the time | Ubuntu 23.10 kernel bug in the step-wise governor | 2 | Kernel update, December 2023 |
| Bootloader failed to detect the fan (Jan–Apr 2025) | 4 | dtparam=cooling_fan=on, then bootloader fix | |
| Board or fan hardware fault | 2 | Replacement board | |
| Back-powered through USB after shutdown | 1 | Power the display from the same supply | |
| No replies at all | 1 | Unknown | |
| Control and configuration | Forcing speed, overrides ignored, bogus RPM reads | 5 | See below |
| Thermal pads | Missing pads on RP1 and RAM; grease on top of pads | 2 | Leave it alone |
Six of the 30 were hardware. Eight were a software or firmware bug, and six of those eight fall in two windows: Ubuntu 23.10 in the last quarter of 2023, and Raspberry Pi’s own bootloader between January and April 2025. If your cooler broke on a date, the date is the diagnosis.
Symptom one: it never spins
It is not hot enough. The most common non-fault. A December 2023 Ubuntu user reported the fan “spins up for a brief 5 seconds when booting, but as soon as Ubuntu appears it stops” and was told that below 50 °C it does nothing (thread 361957). A DietPi user in March 2025 had the same complaint; a maintainer re-imaged, watched it, and reported “Fan speed increases at 60°C” (DietPi forum). Read /sys/class/hwmon/hwmon0/temp1_input before you read anything else.
A bent pin. The JST-SH header is small and the cable goes in one way. In May 2024 a user with a fan that never activated was told to “unplug the connector and check the connector (cable side) and the pins (on the Pi5). Some users bend pins when inserting the connector,” and that if the TACH pin is flat the firmware never sees a fan. They looked: “I found that in fact a pin was bent,” straightened it with the power off, and it spun (thread 370849). This is the one to check before you open a support ticket.
The fan itself. Two threads ended in a replacement. One was a third-party Armor Lite V5 whose owner measured “0 Ohm between tach (yellow) and GND” and got a new unit (thread 386648, April 2025). The other was an official cooler that started stuttering after several months: “when the CPU temp gets above 50, instead of turning on low speed, it will turn on for a second and then off again.” The replacement ran at about 2800 RPM on the first step where the old one managed 800 (thread 366345, 17 replies). The brief quotes a mean time to failure of 379,000 hours at 25 °C; that is a population figure, not a promise about your unit.
The kernel has no fan driver. Fan control on the Pi 5 is done by Linux, not by the firmware. The bootloader only checks whether a fan exists: “The firmware has never provided fan control support, it simply probes for the existence of a fan (or HAT) and control is via the Linux hwmon framework” (timg236, rpi-eeprom #697). So a kernel without the RP1 PWM driver leaves the fan parked after the boot burst. Talos Linux users hit this in April 2026 because the mainline kernel “doesnt ship pwm-rp1 which is the necessary provider” (siderolabs/sbc-raspberrypi #90, still open); the workaround in that thread is a script that maps the RP1 registers directly, and the mainline patch was on the kernel list a month later. A Raspberry Pi OS user who switched from the 16k to the 4k page-size kernel to run Minecraft had the same silence and could only wake the fan with pinctrl FAN_PWM op dl until the next reboot (thread 375887).
The fan’s power comes from the USB rail. This one surprised me. A user whose cooler spun at boot and then ignored an 80 °C SoC had turned the USB ports off with uhubctl to save power. The engineer’s explanation: “On Pi5 fan power comes from USB VBUS i.e. downstream from the USB current limiter / VBUS_EN switch” (thread 388821, June 2025). Turn the ports back on and the fan returns. It also means the fan shares the USB current budget I went through in the power supply post, and a documentation issue asking for the fan’s draw to be published has been open since February 2024 (documentation #3541). A stranger case in the same family: one user’s fan would not run when booting from a Sabrent USB-to-SATA adapter and ran fine from an ASMedia one, idle temperature 66 °C versus 46–53 °C (thread 386162). Nobody in the thread explained why.
Symptom two: it runs at 100 % and never stops
A four-pin fan with 5 V on the supply pin and nothing on the PWM pin runs flat out. Every full-speed report is some version of “nothing is driving PWM,” and there were three distinct reasons.
Ubuntu 23.10, October to December 2023. The Launchpad bug describes the fan at “near maximum speed all the time” with the cooling device stuck at state 4, traced to “a bad rebase of a 6.1 patch to the step-wise fan governor on the 6.5 kernel” that read zero for every trip point (LP #2041741, 16 affected, Fix Released). The forum thread that fed it closed with “The fix is now in the linux-raspi kernel package” (thread 359311). If you are on 24.04 or later this one is history.
The bootloader stopped seeing the fan, January to April 2025. This is the cluster behind most of the “after update” searches. The release notes show the sequence. In December 2024 the bootloader started driving the PWM pin high during early boot so the fan would not scream during network install; in January 2025 it began handing the fan to the OS after the probe. Then reports arrived. On 5 February 2025 a user on the 22 January bootloader found the fan “working on full speed despite low temperature” at 26.8 °C and fixed it by adding dtparam=cooling_fan=on to config.txt, a line the README says should be unnecessary because the overlay is “enabled automatically by the firmware” (rpi-eeprom #660, 22 comments). A second user found it only after a soft reboot, never after a cold boot (#678, 56 comments); the 19 March bootloader added fan-speed logging to vclog to chase it. Then the 19 March build itself broke detection for two fresh boards with the official cooler (#690, 25 comments). The 7 April note explains what had gone wrong: a present fan could show “a maximum observed fan speed of ~300 but a current speed of 0,” which looked like no fan, so the probe now uses the maximum. The maintainer told #660 in May that the 8 May default bootloader “should correct probe failures with the RPi case-fan or the RPi active cooler.” If your Pi is on a 2025 bootloader older than that, sudo rpi-eeprom-update -a is the fix; dtparam=cooling_fan=on is the bandage.
Hardware. Two threads tried all of that and ended with a new board. In one, a brand-new 2 GB Pi 5 ran the fan flat out from power-on; the owner swapped in a cooler from a working Pi and it still ran; pinctrl FAN_PWM op dh did nothing; a loupe showed straight pins. The engineer’s verdict was “This is sounding to me like a hardware fault” and the issue closed as not reproducible (#697). The 41-post forum version from January 2024 has the same shape, with a side note worth repeating: two of the reporters had run rpi-update and were on an unreleased kernel (thread 362647). Do not do that to diagnose a fan.
It runs after shutdown. Not a fault in the Pi. If a USB device, in the reported case a 12 V touchscreen, feeds 5 V back into the board after halt, the fan has supply and no PWM, and “any 4pin fan will run at full speed” (thread 366267). Power the screen from the same switch as the Pi.
Controlling it, and the two ways people get that wrong
The curve is adjustable since January 2024, when a request to customise it got the reply “It’s already on the to-do list” and a pull request the same day (linux #5820). In config.txt, one parameter per line:
dtparam=fan_temp0=55000
dtparam=fan_temp0_hyst=5000
dtparam=fan_temp0_speed=90
dtparam=fan_temp1=65000
dtparam=fan_temp1_speed=150
Two traps from the census. First, do not pack the overrides into one long dtoverlay= line. An August 2026 issue reported that fan_temp1 through fan_temp3 were “silently dropped at real boot” while fan_temp0 and the speeds applied, producing an inverted ladder; the maintainer’s answer was that the 258-character line “is too long for the firmware. Split it into sections of no more than 100 characters” (firmware #2041). Second, do not read fan1_input while writing pwm1 and expect sense. An issue that claimed the tachometer was non-monotonic, with a tidy sweep table, was closed in a day: the kernel’s thermal governor was still in charge and kept overriding the value, so the fan would speed up and shut down a couple of seconds later (linux #7556). If you want manual control, disable the thermal zone first, as the 32-post forcing-speed thread eventually did with echo disabled | sudo tee /sys/class/thermal/thermal_zone0/mode (thread 359778). The non-persistent hack for full speed is pinctrl FAN_PWM op dl; op dh stops it.
Thermal pads: three, and do not touch them
The cooler ships with three pre-applied pads, over the SoC, the PMIC by the USB-C port, and the wireless module. Nothing covers the RP1 or the RAM. An October 2023 thread asked whether that was a mistake and got “They don’t get hot enough to need extra cooling” from a moderator, with the explanation that the board’s ground plane has carried heat away from those parts since the Pi 3B+ (thread 358162). Adding thermal grease on top of the pads got a flat “Don’t do that as it will make things worse!” (thread 361706). The brief goes further: it recommends the cooler is not removed once fitted, because “removal of the Active Cooler will cause the push pins and thermal pads to degrade.” That matters if you are planning a case change later; my case survey has three cases that cannot take the cooler at all, and one of them is the official M.2 HAT+ Compact.
Which one to buy
None of these are on my desk; what follows is store listings read on 2026-09-11 from an Amazon mobile session, one search that surfaced 21 listings, of which I opened seven.
- The official Active Cooler, sold from the Raspberry Pi brand store, was $11.99 with three left in stock. Two other listings with “Official” in the title at the same price are from resellers, one of them a store named UeeKKoo; if you want the unit the census above is about, buy the one in the Raspberry Pi store.
- Argon THRML 30 mm, $12.99, 4.6 stars over 100 ratings, a 30 mm fan on a heatsink that uses the same header and, per the maintainer’s note above, the same probe. I have no thread in this set about it failing, which is different from evidence that it does not.
- GeeekPi Armor Lite V5, $20.25, 4.7 stars over 268 ratings, the tallest of the three. It is also the model in thread 386648 whose tach wire measured shorted to ground; the owner got a working replacement, which is one data point each way.
The honest comparison is that none of the 30 threads was a review. They are failure reports, and the official cooler dominates them because it dominates the installed base. If you run the Pi 5 headless at idle, as the numbers in my NVMe census suggest most people do, the fan will be off nearly all the time regardless of which one you buy, and the heatsink is doing the work. The Mac mini that runs this site has no fan curve I can tune, which is why I measured whether it needed a cooling stand instead.
FAQ
Why does my Raspberry Pi 5 active cooler spin at boot and then stop?
That is normal. The bootloader runs the fan at full speed for about a second to check that a tachometer answers, then hands control to Linux, which keeps the fan off until the SoC reaches 50 °C. It then runs at 29 % duty and does not stop until the temperature falls below 45 °C.
How do I fix a Pi 5 active cooler that runs at 100 % all the time?
Check the date. On Ubuntu 23.10 it was a kernel bug fixed in December 2023. On Raspberry Pi OS with a bootloader from January to April 2025 the firmware sometimes failed to detect the fan; add dtparam=cooling_fan=on to config.txt as a workaround and run sudo rpi-eeprom-update -a to get the May 2025 fix. If the fan still ignores pinctrl FAN_PWM op dh, two threads ended with a replacement board.
Can I change the fan curve on the Raspberry Pi 5?
Yes. Add dtparam=fan_temp0=55000, dtparam=fan_temp0_speed=90 and so on to config.txt, one per line, with temperatures in millidegrees and speeds from 0 to 255. Keep each config.txt line under 100 characters; longer lines lose parameters silently.
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How this was put together: the fan curve is copied from the fan_temp entries in the firmware repo’s overlays README, and the spec figures from the Active Cooler product brief PDF dated January 2026, both read on 2026-09-11. The 30 items are 18 threads on forums.raspberrypi.com found through search results for the fan not spinning or running at full speed, one DietPi forum thread, Ubuntu bug 2041741, siderolabs issue 90, and nine issues in the raspberrypi GitHub organisation found with a title search for “active cooler”, “cooling fan” and “pwm-fan”; each was read in full and sorted by the cause the thread settled on, and quotes carry the poster’s username or role as shown there. Reddit was not reachable from this machine. Prices are from Amazon listings opened on 2026-09-11 in a mobile session. I do not own a Raspberry Pi 5 or any of the coolers and measured nothing here; every product claim is a manufacturer figure or another owner’s report and is labelled as such.