Philips HU4802 User Manual page 23

Problem
No air comes out of the air
outlet.
I do not see visible mist coming
out of the humidifier. Is it
working?
I want to check whether the
humidity sensor works or not.
Possible solution
Put the plug of the humidifier into the wall socket and switch on
the humidifier.
When mist is very fine, it is invisible. This humidifier has a
NanoCloud humidification technology, which produces healthy
humid air from the outlet area without formation of water mist.
Therefore, you cannot see the mist.
Gently blow moist air into the humidity sensor. After a while, the
humidity indication changes. Note that for HU4802, if the initial
humidity indication is already 60 percent, the humidity indication
light stays blue when you blow moist air towards the sensor; for
HU4803, the indication can show the actual humidity level from
20%RH to 95%RH.
EN 23