Unit stops cooling and shows E3; sometimes occurs after long operation.

Safety first: Turn off power at the breaker and wait a few minutes before opening the indoor unit.

• Locate the coil sensor: Remove the front cover and filters. The evaporator thermistor is usually clipped directly onto the aluminum fins or copper tube of the indoor coil.
• Check mounting: Ensure the sensor is firmly clipped to the coil. If it has fallen off, reattach it in the original position so it senses coil temperature correctly.
• Inspect wiring: Follow the sensor wires to the control box. Check for pinched, cut, or corroded wires. Reseat the connector on the PCB.
• Test or replace: If available, measure resistance and compare to spec. If out of range, replace with the correct Sharp evaporator thermistor. Clear the error by power-cycling the unit.
• Board replacement: If a new sensor does not resolve E3, the indoor PCB may be faulty and should be replaced by a technician.