Display shows “Lo” or “LO” and the humidifier does not produce mist.

Safety first: Turn the unit OFF and unplug before removing the tank.

• Refill tank: Remove the water tank, fill with cool, clean water to the indicated MAX line, and reinstall firmly on the base.
• Check tank seating: Make sure the tank is fully seated and not tilted. Many Vicks humidifiers use a valve at the bottom of the tank that must press down on a post in the base to release water.
• Inspect float: On models with a visible float in the base, check that it moves freely up and down. If it is stuck due to mineral deposits, soak the base area in a 50/50 white vinegar and water solution for 20–30 minutes, then gently wipe and rinse.
• Magnetic reed switch: If the float moves but “Lo” remains, the internal reed switch or water level sensor on the base PCB may be faulty and may need replacement.