Warm mist humidifier not producing steam even though the power light is on.

Safety first: Turn OFF, unplug, and allow the unit to cool completely before opening. Water and electricity are a shock hazard.

• Check water level and seating: Ensure the tank is full and correctly seated so water flows into the heating chamber.
• Descale heating chamber: Remove mineral deposits from the heater chamber with a vinegar soak as per the manual. Heavy scale can insulate the heater and trigger safety cutoffs.
• Continuity test (advanced): With the unit unplugged and disassembled, use a multimeter to check continuity across the heating element terminals. If open, replace the heating element assembly. Also check the thermal fuse and thermostat in series with the heater.
• Control board check: If the heater and safety devices test good but no voltage reaches the heater when ON, the control PCB or heater relay may be defective and require replacement.