Error 425 — Phase reversal or phase failure (3Ø outdoor unit wiring, R-S-T-N), connection error on 3 phase input

What does 425 mean?

This error occurs in a 3-phase outdoor unit when the electrical phases are reversed, one or more phases have failed, or there's an incorrect connection on the 3-phase input. This prevents the unit from starting or operating correctly.

• Incorrect wiring during installation (phase reversal)
• Power supply issue from the electrical grid (phase failure)
• Loose or damaged electrical connections at the 3-phase input terminals
• Faulty phase monitoring relay

Click steps to track your progress.

1. 1

   Immediately turn off the main power to the outdoor unit at the electrical panel.

2. 2

   CAUTION: This requires a qualified electrician. Verify the phase connections (R-S-T-N) at the outdoor unit to ensure they are correct and securely tightened.

3. 3

   Check the incoming power supply for any phase failures using a multimeter (only by a qualified professional).

4. 4

   Correct any reversed phases or loose connections.

5. 5

   Restore power after the wiring has been verified and corrected. Do not attempt to troubleshoot without professional electrical knowledge.