Indoor unit displays F0 and the unit does not cool or heat properly.

Safety first: Refrigerant is under high pressure and must only be handled by certified personnel. Do not attempt to open service valves or connect gauges yourself.

• Step 1 – Visual inspection for leaks:
  • Look for oil stains on flare joints at the indoor and outdoor units.
  • Check around the service valves and coil connections for oily residue or corrosion.
• Step 2 – Check airflow and filters:
  • Ensure filters and coils are clean to rule out airflow-related performance issues.
• Step 3 – Observe operation:
  • Run the unit and feel the large copper pipe at the outdoor unit; it should be cool in cooling mode.
  • If both pipes are nearly ambient and F0 appears, refrigerant charge is likely low.
• Step 4 – Call a certified technician:
  • A technician must locate and repair leaks, evacuate the system, and recharge with the correct type and amount of refrigerant specified by Hisense.
  • Operating with low refrigerant can damage the compressor.