Indoor unit displays F8, system may not operate in certain modes

Safety first: Turn off power before modifying control wiring.

Steps:

• Check controllers: If multiple remote controllers are installed, ensure they are not commanding conflicting modes (e.g., one in cooling, one in heating).
• Central control: If a central controller (e.g., Mitsubishi Electric centralized controller) is installed, check its settings for lockouts or mode restrictions.
• Group wiring: Verify that group control wiring is correct and that only intended units are grouped.
• Reset controllers: Power cycle controllers and the system to clear temporary conflicts.