F5
Outdoor Unit Protection Device Connector Open
Mitsubishi Electric · PAR-21MAA MA Remote Controller
What does F5 mean?
A protection device connector on the outdoor unit is open, preventing proper system operation and communication. This leads to the remote controller displaying 'PLEASE WAIT'. The outdoor board LED will blink green once and red twice alternately after system startup.
Common Causes
- Open circuit detected at the outdoor unit's protection device connector.
- Loose or disconnected wiring at the protection device terminal.
- Faulty protection device requiring replacement.
- Internal wiring break within the outdoor unit to the protection device.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Locate and visually inspect all protection device connectors on the outdoor unit for disconnections or looseness.
- 2
Securely reconnect any identified open protection device connectors on the outdoor unit.
Verified technical data. Last updated: March 2026
Related Faults
Source: Mitsubishi Electric PAR-21MAA MA Remote Controller