How do the red and blue indicator lights in my Philips Humidifier work?

When the desired humidity level is reached, the color of the humidity indicator light is blue. When the humidity level is not reached, the color of the humidity indicator light becomes red.

There is a float (a floating ball) inside your Philips Humidifier’s tank. When the water level becomes low, the float activates a water level switch and this will activate the red indication.

Note: sometimes, this floating ball can be stuck and fail to activate the water level switch. When this happens, your humidifier will not display a low water indicator. You can solve this by moving this ball with your hand.