Indoor unit shows F6; unit may stop in heating mode; often related to defrost or outdoor coil temperature.

Safety: Turn off power at the breaker. Outdoor coils and fins are sharp; wear gloves.

Steps:

• 1. Locate defrost sensor: On Airwell heat pump models, a dedicated NTC sensor is often clipped to the outdoor coil in the lower section to detect frost.
• 2. Check placement: Ensure the sensor is firmly attached to the coil where frost typically forms. Reattach if loose.
• 3. Inspect wiring: Follow the sensor wires to the PCB. Look for damage or loose connectors. Reseat the plug.
• 4. Test sensor: With power OFF, disconnect and measure resistance. Compare with other NTC sensors at similar temperature. Replace if readings are abnormal.
• 5. Replace sensor: Install a new Airwell defrost sensor and secure it in the correct location.
• 6. PCB diagnosis: If sensor and wiring are good, the outdoor PCB defrost algorithm may be malfunctioning and require board replacement by a technician.