HIT

Hitachi 45

Critical

Set Free Sigma / IVX (FSXN) — Activation of the high-pressure increase protection device

Hitachi 45: Activation of the high-pressure increase protection device This fault typically halts operation and needs immediate attention.

Possible causes

Closed stop valve or locked expansion valve
Abnormal high-pressure sensor or incorrect indoor/outdoor unit connection

Check steps

Inspect stop valve status, check PCB connectors and test thermistors
Verify electrical and refrigerant connections, replace faulty components

Affected parts

High pressure sensor
Stop valve
Expansion valve

Safety note

High system pressure (up to 3.8 MPa) — safely relieve pressure before working.

Source: Hitachi resmi servis kılavuzu (bağımsız çift-doğrulandı) — Hitachi FSXN Series Service Manual, §8 Troubleshooting by alarm code, p.224 (manualslib.com/manual/2375584) — flowchart for "Activation of the high pressure increase protection device": "In the case that the compressor operates under a greater discharge pressure (Pd) condition than 3.8 MPa for 1 minute, all the comp…

Reviewed by Anıl Güzeldemir — in the refrigeration machine room since 2006, developer of Enthalio.

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