it keeps showing 'FULL' but the basket is only half full of ice, how do i fix the sensor?

Diagnosis

The "FULL" indicator on the Sentern Portable Clear Ice Maker is triggered by an infrared (IR) beam sensor system. This system consists of an emitter and a receiver located on the interior walls of the ice chamber. When ice cubes pile up and break the beam, the machine assumes the basket is at capacity and halts production to prevent ice from backing up into the cooling mechanism or damaging the internal dispensing arm. A false "FULL" reading occurs when the sensor is "blinded." This is typically caused by a thin film of mineral deposits (limescale) from hard water, a stray ice chip wedged against the sensor lens, or condensation droplets clinging to the infrared window. Because the sensor operates on light refraction, even a tiny, translucent piece of ice or a smudge of grime can reflect the beam back into the receiver, tricking the logic board into thinking the basket is overflowing even when it is only half-full. To confirm this is a sensor issue and not a mechanical failure, check if the "FULL" light persists even after you have completely emptied the ice basket. If the light remains on with an empty chamber, the sensor is either obstructed or has suffered a calibration drift due to moisture infiltration.

How to Fix It

1. Power down the unit by pressing the "ON/OFF" button and completely unplug the power cord from the wall outlet to prevent any electrical shorts during cleaning.
2. Remove the ice basket entirely from the unit. This gives you clear access to the interior walls of the ice chamber.
3. Locate the infrared sensor. Look for a small, circular, clear or slightly tinted plastic window embedded in the inner wall, usually positioned opposite the side where the ice drops from the freezing tray.
4. Dampen a cotton swab with a small amount of distilled water or a 50/50 mixture of white vinegar and water. Gently scrub the sensor window to remove calcium buildup and mineral scales.
5. Use a second, dry cotton swab to buff the window completely dry. Any lingering water droplets can refract the IR beam and trigger a false "FULL" signal.
6. Inspect the area around the sensor for any "ice bridges"—small shards of ice that have frozen to the wall. Carefully chip these away using a plastic utensil; never use metal tools as you may scratch the sensor lens or puncture the coolant lining.
7. Ensure the ice basket is seated perfectly flush against the base. If the basket is tilted or not fully inserted, it can sometimes interfere with the sensor's line of sight.
8. Plug the unit back in and press the "ON/OFF" button to reboot the system. The "FULL" light should now be extinguished.

If That Didn't Work

• Perform a Hard Reset: Unplug the unit for at least 10 minutes. This allows the internal capacitors to discharge and resets the control board's sensor logic, which can clear "ghost" errors stored in the temporary memory.
• Deep Descale the Interior: If you have hard water, minerals may have seeped behind the sensor bezel. Fill the reservoir with a dedicated descaling solution or a citric acid mix, run a full cycle, and then run two cycles of plain distilled water to flush the system.
• Check for Basket Deformation: Inspect the plastic ice basket for any warping or cracks. If the basket is slightly bowed outward, it may be pushing ice cubes into the sensor's path prematurely, triggering the "FULL" light before the basket is actually full.
• Adjust Unit Leveling: Place a bubble level on top of the ice maker. If the machine is tilted forward or to the side, the ice will pile up unevenly, hitting the sensor on one side while leaving the rest of the basket empty. Adjust the surface to ensure it is perfectly level.

Heads Up

• Avoid Chemical Cleaners: Never use bleach, ammonia, or abrasive scrubbing pads on the sensor window. These can etch the plastic, making the sensor permanently "blind" and causing the machine to stop producing ice indefinitely.
• Use Distilled Water: To prevent the mineral buildup that causes these sensor failures, use distilled water instead of tap water. This drastically reduces the frequency of "FULL" error malfunctions.
• Prevent Overfilling: Do not manually pack the ice basket down to fit more ice. This can push cubes into the sensor area and potentially bend the internal dispensing arm.
• Temperature Management: Ensure the unit has at least 6 inches of clearance on all sides. If the unit overheats, condensation forms more rapidly on the interior walls, which increases the likelihood of sensor interference.