Mitsubishi Electric Diagnostics & Fault Manuals

Manufacturer of Mitsubishi Electric systems and diagnostic equipment.

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Equipment Models

Hardware families produced by Mitsubishi Electric

1 Series

Ecodan PUZ-WZ R290 Monobloc Series

1 guides

Class: HVAC & Heat Pumps Equipment

Browse Fault Codes

Indexed Error Codes for Mitsubishi Electric

Machine-verified error code diagnostic walkthroughs

1 Manuals

CODE P8 Ecodan PUZ-WZ R290 Monobloc Series Critical

Heat Exchanger Freeze Protection Lockout

The P8 fault indicates an active freeze protection lockout on the plate heat exchanger (HEX). The outdoor controller detected water or plate surface temperatures dropping below safety limits (typically < 3°C to 5°C) during heating, cooling, or defrost modes, triggered to prevent catastrophic rupture of the brazed plate exchanger by expanding ice.

⏱ 45-60 Mins Troubleshoot →