# Buzzing sound from controller fan

**URL:** <https://klipper.discourse.group/t/buzzing-sound-from-controller-fan/11031>\
**Category:** General Discussion\
**Created:** [October 17, 2023, 9:23pm UTC](https://klipper.discourse.group/t/buzzing-sound-from-controller-fan/11031 "2023-10-17T21:23:01Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![backspace](https://avatars.discourse-cdn.com/v4/letter/b/e19adc/32.png) [@backspace](https://klipper.discourse.group/u/backspace)\
**Post date:** [October 17, 2023, 9:23pm UTC](https://klipper.discourse.group/t/buzzing-sound-from-controller-fan/11031/1 "2023-10-17T21:23:01Z")

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### Basic Information:

Printer Model: Custom  
 MCU / Printerboard: BTT SKR Mini E3 V3  
 klippy.log: [klippy.zip](https://klipper.discourse.group/uploads/short-url/8Rod2eIifN2hhqomRtZ2C7HaGn1.zip) (43.7 KB)

### I have a 2 pin 24v fan for cooling a BTT SKR Mini E3 V3. The fan is connected to the FAN2 pins. The fan works as expected using controller\_fan in Klipper, but if I run the fan at anything less than 100%, it makes a vibrating/buzzing noise. I have tried several fans, and they all behave the same. If the fans are removed and connected to a lower voltage (3v and 5v) they run whisper quiet. Is there a way to stop the fan from buzzing when run at lower speeds?

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**Author:** ![LifeOfBrian](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/lifeofbrian/32/2380_2.png) [@LifeOfBrian](https://klipper.discourse.group/u/LifeOfBrian)\
**Post date:** [October 18, 2023, 6:30am UTC](https://klipper.discourse.group/t/buzzing-sound-from-controller-fan/11031/2 "2023-10-18T06:30:02Z")

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Sounds like the PWM humming.  
If you would have attached the requested klippy.log one could check what frequency you maybe set for those printer port.

Long story short: **always attach the klippy.log**

For your issue: it is often a compromise between noise and range of control of the fan via PWM.  
Read here:  
[https://www.klipper3d.org/Config\_Reference.html#fans](https://www.klipper3d.org/Config_Reference.html#fans)

As I do not think your MCU supports hardware PWM you should only play with

```auto
cycle_time: 0.010

```

It is the reciprocal value (in seconds) of the frequency for PWM control.  
Default is 10 ms or **0.010** what equals 100 Hz.  
Some fans might work better with 1000 Hz or even more.  
Depending on the set **cycle\_time** you might not be able to properly control the fan speed.  
Meaning the fan might then already spin with 100% RPM although being set to only 60 %.

And of course the fans should support PWM control.

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**Author:** ![backspace](https://avatars.discourse-cdn.com/v4/letter/b/e19adc/32.png) [@backspace](https://klipper.discourse.group/u/backspace)\
**Post date:** [October 18, 2023, 7:27am UTC](https://klipper.discourse.group/t/buzzing-sound-from-controller-fan/11031/3 "2023-10-18T07:27:53Z")

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Thanks LifeOfBrian. I have attached the klippy.log - lesson learned.

I’ll experiment with the cycle\_time setting tomorrow morning (NZ time)

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**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/klipper/original/1X/64419bf2aac6639e6ef5cef200dcd456b0a01ac3.png) [@system](https://klipper.discourse.group/u/system)\
**Post date:** [December 17, 2023, 7:28am UTC](https://klipper.discourse.group/t/buzzing-sound-from-controller-fan/11031/4 "2023-12-17T07:28:20Z")

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