If your fan is operating correctly but the lights are not visible, it's possible that the brightness has been dimmed.
To adjust the brightness:
Press and hold the On/Standby button.
While holding the On/Standby button, tap the fan speed button with your other finger to adjust the brightness level.
If the brightness is at the lowest setting, it will increase by one level.
If the brightness is at the highest setting, it will decrease by one level.
If changing the brightness doesn’t improve the situation, please reach out to us here: https://www.blueair.com/customer-support.html