Need help writing a sketch

Hello!

Need help in writing a sketch to control the cooling fan of the car.
Engine with PWM regulation, works like this:
Frequency 25 Hz, and the duty cycle from 13% to 70%

Only the frequency from the Arduino nano and the signal from the resistive temperature sensor are needed (below is a screenshot of the sensor parameters)
Start of operation from a temperature of 91 degrees Celsius, to 96.
5 steps of a duty cycle will be enough, 20% 30% 50% 60 and 70% And in case of failure of the temperature sensor, emergency mode is activated by 50%
Then this sketch will be adjusted to the temperature conditions, this is preliminary.

What library is better to write with? “Servo” or “Analog write”?

Thank you in advance!

Analog write actually varies the pwm of its output pin - it’s not a true analog signal - that’s what you want .

IMHO is a waste of time and effort to control your cooling fan like this , just have it on /off.