F1
Reverse Phase Detection
Mitsubishi Electric · R410A Systems
What does F1 mean?
The outdoor unit has detected that the incoming main power phases are reversed. This condition prevents proper operation of the outdoor unit and can lead to damage if not corrected.
Common Causes
- Incorrect phase sequence of incoming power.
- Motor connected to reversed phase power supply.
- Protection against damage from incorrect phase rotation.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Verify the phase rotation of the incoming power supply at the outdoor unit's main power input terminals using a phase rotation meter.
- 2
Correct the phase sequence at the main power supply or the unit's input terminals (L1, L2, L3) as necessary.
Verified technical data. Last updated: March 2026
Related Faults
Source: Mitsubishi Electric R410A Systems