Digital Essick Air humidifier displays an F or flashing F and will not run; unit may beep repeatedly.

Safety first: Turn the unit off and unplug it before handling the tank or internal components.

• Check water level: Remove the water bottle and verify it is filled. Refill with cool, clean water if empty.
• Inspect the bottle cap and valve: Ensure the Essick Air bottle cap and valve assembly are intact and not clogged with mineral deposits. Press the valve pin to confirm water flows freely. Clean with vinegar if needed.
• Reseat the bottle: Place the bottle back onto the base, aligning it with the valve opening. Push down firmly until you see air bubbles rising, indicating water is flowing into the reservoir.
• Check the float or level sensor: On models with a mechanical float, verify it moves freely and is not stuck by scale. On models with an electronic water level sensor, clean the sensor area in the base with a soft cloth.
• Power up: Plug the unit back in and turn it on. The F code should clear once the base has sufficient water.

If the F code persists with a full, properly seated bottle, the float switch or water level sensor may be faulty and require replacement.