Display shows E3; unit may start but quickly shut down or fail to complete a cycle.

Warning: Refrigeration system diagnosis involves high pressures and specialized tools. Do not open the sealed system unless you are EPA‑certified.

Basic checks you can do:

• Unplug the unit and remove the ice bin to expose the evaporator plate.
• Inspect the evaporator plate for heavy scale, mineral deposits, or physical damage. Clean with a manufacturer‑approved nickel‑safe ice machine cleaner if scaled.
• Verify that the evaporator thermistor is firmly clipped to the correct location on the plate or tubing and has good thermal contact (no loose or dangling sensor).
• Check the condenser coil (usually at the front or rear bottom) for dust and lint. Clean thoroughly with a soft brush and vacuum to improve heat exchange.
• Restore power and observe a cycle: the evaporator should frost evenly. If only part of the plate frosts or frost is very slow to form, there may be a sealed system issue (low charge, restriction, weak compressor).

Next steps: If cleaning and sensor repositioning do not clear E3, have a qualified Marvel service technician check system pressures, superheat/subcooling, and compressor performance. Sealed system repairs require professional service.