My display is reading green but the fan is working at high speed
There may be times when the display is showing green but the fan speed is still high. This is due to the machine always trying to maintain high air quality.
For example, in a room with leaky windows, the machine has to work harder via a higher fan speed to maintain a high air quality.
If you the fan to be quieter, you can choose to change the airflow direction to face backwards, or turn the machine to manual mode and lower the airspeed.