It should work without disabling the fan but you can read this
- https://docs.braiins.com/os/open-source-en/Configuration/index_configuration.html#temperature-and-fan-control

You can also try to repair the fan maybe that fan that gives you a false signal have a cut wire connection if you have a multimeter check the connection from the yellow wire it should be for RPM signal and the BLUE one should be the PWM usually if this one has no connection the signal for PWM always fixed at 100%.
So focus on the yellow wire you can check the terminal or plug if there is corrosion clean it with petrol or laquer flo thinner or if you don't have then you can try alcohol it would also work. Or you can replace/jumper the yellow wire directly to the control board.