Hitachi 47

High

Set Free Sigma / IVX (FSXN) — Vacuum operation protection / excessively low suction pressure

Hitachi 47: Vacuum operation protection / excessively low suction pressure This fault noticeably affects operation.

Possible causes

Refrigerant shortage, leak, or closed stop valve
Locked (fully closed) expansion valve or faulty outdoor fan motor

Check steps

Verify refrigerant charge volume, inspect for leaks, open stop valves
Test pressure sensor and electronic expansion valve operation, replace defective components

Affected parts

Low pressure sensor
Expansion valve
Outdoor fan motor

Safety note

Depressurize the system before refrigerant work and watch for refrigerant release.

Source: Hitachi resmi servis kılavuzu (bağımsız çift-doğrulandı) — Hitachi FSXN Series Service Manual, §8 Troubleshooting by alarm code, p.225 (manualslib.com/manual/2375584, page=225) — not p.220 as originally cited (p.220 in that pagination is code 3b, unrelated). Verified text: "Activation of the low pressure decrease protection device (Vacuum operation protection)... when the suc…

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

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