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. 1

    Locate and visually inspect all protection device connectors on the outdoor unit for disconnections or looseness.

  2. 2

    Securely reconnect any identified open protection device connectors on the outdoor unit.

Browse all codes in this manual (26)
Verified technical data. Last updated: March 2026

Related Faults

Source: Mitsubishi Electric PAR-21MAA MA Remote Controller