Fan control iMac running

[PJC]

Hi

I'm new to Linux.. so hoping I can, firstly, get some help.. and secondly that I can understand how to implement the suggestions! Here goes..

I have an iMac 2009. I recently upgraded from the HDD to a SSD, but in that process the HDD sensor is now not functioning. This means that the fan that is meant to keep the HDD/SSD cool runs at its maximum speed.

When I was on Mac OS I was able to download several apps that could control the HDD fan and lower the speed when required (which was most of the time).

Now that I'm on Linux Lite, I am struggling to find a way that I can control the HDD fan.

I've tried several forums suggestions:

https://ubuntuforums.org/showthread.php?t=42737
https://www.linuxliteos.com/forums/other-17/fan-runs-constantly/
https://www.reddit.com/r/linux4noobs/comments/v5vems/fan_control_software_for_linux/
https://www.linuxliteos.com/forums/on-topic/cpu-fan-controle/

Most (I think all) refer to sensors... but the nuance with my situation is that there is no sensor present! Is there a way to simply change the fan speed without addressing anything about its sensor?

Hoping for some help!

PJC