Cannot get fan speed with lm_sensors

Since I blew air into the fan “exhaust pipes” (?) of my PC, the fans make a funny sound.

Like a low-pitched noise.

I guess I have broken something, maybe I have broken a fan and now all the job must be done by the other fan?

So I’m trying to get the fan speed of my fans from Fedora, But I am unable to do so.

In order to get the fan speed, I followed the instructions here.

So I have issued:
sudo dnf install lm_sensors

sudo sensors-detect
and pressed “Enter” to all the questions.

The above command tells me that the configuration file was saved into '/etc/sysconfig/lm_sensors`.

Here is the content of that file:

$ cat /etc/sysconfig/lm_sensors 
# Generated by sensors-detect on Sat Jul 10 08:01:46 2021
# This file is sourced by /etc/init.d/lm_sensors and defines the modules to
# be loaded/unloaded.
# The format of this file is a shell script that simply defines variables:
# HWMON_MODULES for hardware monitoring driver modules, and optionally
# BUS_MODULES for any required bus driver module (for example for I2C or SPI).


Now to get the fan speed I try the command:
sudo sensors

This is its output:

$ sudo sensors
Adapter: Virtual device
temp1:        +52.0°C  

Adapter: PCI adapter
Composite:    +27.9°C  (low  = -273.1°C, high = +69.8°C)
                       (crit = +79.8°C)

Adapter: ISA adapter
Package id 0:  +48.0°C  (high = +100.0°C, crit = +100.0°C)
Core 0:        +45.0°C  (high = +100.0°C, crit = +100.0°C)
Core 1:        +48.0°C  (high = +100.0°C, crit = +100.0°C)
Core 2:        +47.0°C  (high = +100.0°C, crit = +100.0°C)
Core 3:        +48.0°C  (high = +100.0°C, crit = +100.0°C)
Core 4:        +46.0°C  (high = +100.0°C, crit = +100.0°C)
Core 5:        +47.0°C  (high = +100.0°C, crit = +100.0°C)

Adapter: Virtual device
temp1:        +59.0°C  

Adapter: ACPI interface
in0:          15.97 V  
curr1:         1.58 A  

As you can seen there is only the temperature, not the fan speed.

How do I get the fan speed?

Blowing air into the fan exhausts was likely not a good idea. It moves collected lint/dust back into the air passages and the fan instead of out of the machine. The noise you are hearing is likely the fan hitting the relocated lint/dust mass.

I would suggest that you open the system and thoroughly clean the air passages, including inside the fan.

As far as lm-sensors goes, when you ran sensors-detect and it did not configure the fan sensors it is likely there are no speed sensors that lm-sensors can read. On my laptop, which is less than 2 years old, there seem to be no sensors for the fan speed, and that may be the case for you as well.

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Yeah probably not a good idea.

I would need technical assistance to clean the air passage, but for now I get tolerate the noise.

I think if the fan would get broken the system would not boot altogether?

Also, I find it very strange that I lack sensors to detect the fan speed. My laptop is also less than 2 years old.

Is it possible that the kernel don’t support the sensor? How do I find out if I for real lack sensors to detect fan speed or if I have it but the kernel does not support it?