De'Longhi dehumidifier's humidifier function (on combo humidifier/dehumidifier models) does not produce visible mist or raise humidity.

Safety first: Unplug the unit before servicing the humidifier section.

Step-by-step:

• 1. Check water level: Ensure the humidifier reservoir is filled with clean water and properly seated so its valve opens.
• 2. Clean transducer or wick: For ultrasonic models, gently clean the metal transducer disc with a cotton swab and white vinegar to remove scale. For evaporative models, inspect the wick filter and replace if hardened or discolored.
• 3. Inspect mist outlet: Make sure the mist outlet is not blocked by dust or mineral deposits. Wipe clean with a damp cloth.
• 4. Test in a small room: Run the unit in a smaller closed room and monitor humidity with a hygrometer. If there is no change, the humidifier pump or control may be faulty.
• 5. Replace components: Replace the ultrasonic transducer module, wick filter, or humidifier pump as appropriate for your model.