Indoor unit displays E3 and the unit stops; may occur during defrost or heavy load conditions.

Safety first: Turn off power at the outdoor disconnect or breaker. The outdoor unit contains high voltage and moving fan blades.

• Step 1 – Access the outdoor PCB and sensor:
  • Remove the top or side service panel of the outdoor unit.
  • Locate the thermistor attached to the condenser coil (often clipped or strapped to the tubing).
• Step 2 – Inspect wiring and connector:
  • Follow the sensor wires to the outdoor PCB.
  • Ensure the connector is firmly seated and free of corrosion or water ingress.
  • Check the cable for cuts, UV damage, or rodent bites.
• Step 3 – Test the sensor (if qualified):
  • Disconnect the sensor from the PCB and measure resistance at ambient temperature.
  • Compare to Hisense specifications; open or short readings indicate a failed sensor.
• Step 4 – Replace the sensor if defective:
  • Unclip or unstrap the old sensor from the coil.
  • Install the new Hisense-compatible outdoor coil sensor in the same location.
  • Secure it tightly to ensure good contact with the coil.
• Step 5 – If sensor tests OK: The outdoor PCB may be faulty. Due to high-voltage circuitry and refrigerant controls, PCB replacement should be done by a professional.