You could’ve saved this circuit diagram as an image and post here. It is very difficult to read the circuit.
I can see a controller, motor driver and an ADC. The ADC converts the analog temeprature value to digital so that the controller can understand and the code will control the motor, most probably using the pwm method.
One thing I’ve noted that there is no temeperature sensor, or may be I’m not able to see it.