it shows the 'add water' light but the tank is definitely full, i just filled it.

Diagnosis

The "Add Water" indicator on a Crownful Countertop Ice Maker is triggered by a magnetic float switch located inside the reservoir. When the water level is sufficient, the buoyant float rises, moving a magnet close to a reed switch that signals the control board to begin the freezing cycle. If the light remains on despite a full tank, the float is physically stuck in the "down" position or the magnetic connection has been disrupted by mineral buildup. This most commonly occurs due to calcium and magnesium deposits (limescale) from hard water, which create a gritty friction layer on the inner walls of the reservoir, pinning the float in place. In some cases, air bubbles can become trapped beneath the float, or the float may have become slightly offset, causing it to wedge against the plastic housing. You can confirm this by gently tilting the machine; if the light flickers off momentarily, the float is simply stuck and not floating freely on the water's surface.

How to Fix It

To resolve a stuck float sensor and clear the "Add Water" error, follow these precise steps:

1. Power down the unit and unplug it from the wall outlet to prevent any electrical shorts during the cleaning process.
2. Remove the water reservoir completely from the machine. Empty the water into a sink.
3. Inspect the interior of the tank for a small, white plastic cylinder (the float). If it is sitting at the bottom despite the tank being full, it is jammed.
4. Prepare a descaling solution: Mix 2 cups of warm distilled water with 1/2 cup of white distilled vinegar.
5. Pour the solution into the reservoir and let it soak for at least 45 to 60 minutes. This breaks down the calcium carbonate crystals that are gripping the float.
6. While the solution is inside, gently shake the reservoir from side to side. You should feel the float "snap" or slide upward.
7. Rinse the reservoir thoroughly with fresh water to remove all vinegar residue.
8. Reinstall the reservoir and ensure it is seated firmly. Plug the machine back in and press the "Reset" or "Power" button to clear the cached error code.

If That Didn't Work

If the vinegar soak does not clear the light, try these advanced troubleshooting steps:

• Manual Float Manipulation: Use a thin, blunt plastic tool or a straw to gently nudge the float upward from the top of the reservoir. If the light turns off the moment you push the float up, the float is likely warped or the water surface tension is preventing it from rising.
• Sensor Cleaning: Use a cotton swab dipped in isopropyl alcohol to clean the contact area where the reservoir meets the machine base. Debris or slime buildup on the external sensors can sometimes interfere with the signal transmission.
• Hard Reset: Unplug the machine for a full 10 minutes. While unplugged, press and hold the power button for 15 seconds to discharge any remaining capacitors on the main PCB. This forces the logic board to re-poll the water sensor upon restart.
• Check for Air Locks: If you recently moved the machine, an air bubble may be trapped in the pump line. Gently rock the machine back and forth while it is powered on to force the air bubble out of the intake valve.

Heads Up

Keep these maintenance tips in mind to prevent the sensor from failing again:

• Use Filtered Water: Always use distilled or filtered water to minimize the accumulation of mineral scale that jams the float sensor.
• Weekly Flush: Once a week, run a cycle of warm water and lemon juice or a commercial descaler through the machine to keep the internal tubing and sensors clear.
• Avoid Overfilling: Do not fill the reservoir past the "MAX" line, as this can occasionally cause the float to lodge against the top lid, triggering a false "empty" reading.
• Dry Storage: If storing the machine for the season, ensure the reservoir is completely dry and the float is moving freely before packing it away to prevent mold-induced sticking.