E9 error code, compressor may run continuously or not at all, temperature drifts

Safety: Disconnect power before working on external cabinet components.

• Locate ambient sensor: On many CELLA models, the ambient sensor is mounted near the front grille or behind a vent on the side of the cabinet.
• Inspect mounting: Ensure the sensor is not hanging loose or touching hot components. Re-secure it in its original position.
• Check wiring: Follow the sensor leads to the harness. Look for damage from rodents, cleaning, or movement. Reseat the connector.
• Test sensor: Measure resistance at room temperature and compare to CELLA's ambient NTC spec. Replace the ambient temperature sensor if readings are incorrect.
• Control board: If the sensor is good but E9 persists, the ambient sensor input on the main control board may be defective.