No Fan detection under Gnome Ubuntu 16.04 Edit

Update.

Today I tried, installing the fancontrol package. After running it, I get on screen:

sudo pwmconfig
# pwmconfig revision 6243 (2014-03-20)
This program will search your sensors for pulse width modulation (pwm)
controls, and test each one to see if it controls a fan on
your motherboard. Note that many motherboards do not have pwm
circuitry installed, even if your sensor chip supports pwm.

We will attempt to briefly stop each fan using the pwm controls.
The program will attempt to restore each fan to full speed
after testing. However, it is ** very important ** that you
physically verify that the fans have been to full speed
after the program has completed.

/usr/sbin/pwmconfig: There are no pwm-capable sensor modules installed

I don't remember if there was something detected in Gnome Ubuntu 14.04 using this application, but I do remember that at least lm-sensors was able to detect the fan speed sensor.

Update.

After a few ups and downs using Gnome Ubuntu 16.04 (thermal control was out of control, getting to 71ºC just showing the desktop and browsing) I decided to switch back to 14.04.

After fresh installing it, same issue came up. At least, lm-sensors does not detect the fan sensor again. I realized that the installed kernel was 4.2.X.

If I'm not wrong, before upgrading to 16.04, my system was running the 3.X kernel branch. Could that be the problem? Could be the new kernel branch the responsible for this behaviour?

Now in fresh 14.04, i8kctl gives the fan speed, nevertheless in 16.04 gave nothing (well, the fan did not startup).

Update.

Yesterday I upgraded (within the OS) from 14.04.05 to 16.04.

Tried the usual stuff installing lm-sensors with the same results as before.
Typing i8kctl I got the fan speed, and it was still working after the upgrade (good!).

Here comes the weird thing. I installed the Freon gnome-shell extension, which monitors a few interesting hardware things including fans speeds. And it DOES work. It shows the system fan speed (the only fan running on this system). Then, I tried again to run sudo sensors-detect and no fan sensor was detected.

I've been running for a while gnome-shell extension called system-monitor. Till 14.04 it worked well showing the fan speed among other things. Running that extension now, after installing the Freon extension, works again and gives the fan speed.

For the information shown in this extension, the sensor that monitors the fan speed is called Dell_smm-Fan1. Before running the Freon extension there was no sensor available for fans

I'm not technician, nor programmer, just an end user, so I think my problem has been solved (I don't know yet how).

Seem to me, that lm-sensor is missing something during the detection, but probably I am completely wrong. I would be glad to carry out any tests or uploading any dumps need to find out more about this, but I'm gonna need some guidance for that.

Regards.

Marking server-notriage as this sounds like a laptop-only problem.

Status changed to 'Confirmed' because the bug affects multiple users.