Humidifier powers on but produces no mist at all.

Safety: Unplug and empty the humidifier before inspection.

Steps:

• Check water level and placement: Ensure the tank is full enough and properly seated. Many Levoit models will not mist if the tank is misaligned.
• Inspect transducer: Look at the metal disc at the bottom of the water chamber while the unit is on (from a safe distance). If there is no visible vibration or rippling, the transducer is not working.
• Descale: Unplug, then clean the disc with a cotton swab dipped in white vinegar to remove mineral deposits. Rinse with clean water and dry.
• Check wiring underneath: Remove the base cover and verify the transducer wires are firmly connected to the PCB and not burned or broken.
• Replace transducer: If cleaning and wiring checks do not restore mist, replace the ultrasonic transducer assembly with a compatible Levoit part.
• Replace PCB if needed: If a new transducer still does not operate, the ultrasonic driver on the main PCB is likely defective and the board should be replaced.