Following Conditions Are Normal
Symptom
Snapping noise when plugging power cord into AC outlet
Purifier body vibration during the “Max” operation
No vapor or mist visible
Bubbling noise
Humidity level indication differs from hygrometer reading
Shutter is stopped midway
Clicking noise during operation
Rocking water surface in the water tank
Indicators repeatedly turn on and off one after another, and the fan is stationary
Pressing the eco button operates the ionization setting / release of the other Hitachi air purifier with ionizing function.
Or, pressing the ionizing button on the remote controller for the other Hitachi air purifier with ionizing function operates the setting / release of eco operation.
The fan is stopped.
Cause
Electric components are energized when power is supplied. This is normal.
Vibration is caused by fan rotation. This is normal.
As the unit employs evaporation system that produces moisturized air by passing air stream through the humidifying filter, no vapor or mist is visible. This is normal.
The noise is produced by air bubble when water in the water tank is supplied to the water tray. This is normal.
Humidity level is indicated as a guide only. Also an environmental difference in the room may cause different indications.
There is no problem in performance even if the shutter is not fully opened. This is normal.
It is a switching sound of the shutter. This is normal.
It is caused by vibration during operation. This is normal.
The unit is in the demo mode. Unplug the power cord once, wait for a few seconds, and then insert the power plug into AC outlet.
The signals from the remote controllers are the same. Both functions respond. This is normal.
When eco operation is selected, the fan
may stop. 
Troubleshooting Guide