Unit stops cooling or heating, indoor display shows E2

Safety first: Turn OFF the breaker and wait at least 3 minutes before opening the indoor unit.

Steps:

• Access the sensor: Open the front panel and remove the air filters. Locate the small thermistor probe near the air intake or evaporator coil, usually clipped to the plastic frame or coil.
• Check connection: Follow the thin sensor wires to the indoor PCB. Ensure the small connector is fully seated on the board and not corroded or damaged.
• Inspect the sensor: Look for broken wires, crushed insulation, or a sensor that has fallen out of its clip. Re‑clip it so it is in the airflow but not touching metal parts directly (unless designed to).
• Clean dust: Gently clean heavy dust from around the sensor with a soft brush; excessive dust can cause incorrect readings.
• Test operation: Restore power and test. If E2 returns immediately, the thermistor is likely open/shorted and should be replaced with a Hitachi‑specified sensor.

Note: Replacing the thermistor is usually straightforward but requires correct part matching by model number. If a new sensor does not clear E2, the indoor PCB sensor circuit may be defective.