HIT

Hitachi 01

Medium

Set Free Sigma / IVX (FSXN) — Activation of the indoor unit protection device (float switch)

Hitachi 01: Activation of the indoor unit protection device (float switch) This fault usually isn't an immediate stop, but should be checked soon.

Possible causes

Clogged condensate drain line, high water level in drain pan
Faulty float switch (FS) or incorrect wiring at CN14

Check steps

Check DC12V between #2 and GND of CN14; inspect drain pan for clogging
Measure float switch continuity at low water level; replace switch or PCB if faulty

Affected parts

Float switch (FS)
Indoor unit PCB
Drain pan
CN14 connector

Safety note

Disconnect power before working on the unit. Water leakage can damage electrical components.

Source: Hitachi resmi servis kılavuzu (bağımsız çift-doğrulandı) — Hitachi FSXN Series Service Manual, §8.3.1 "Alarm codes", p.176 (source: manualslib.com/manual/2375584/Hitachi-Fsxn-Series.html?page=176): Code 01 = "Activation of the Indoor unit protection device" (RUN indicator flashes, ALARM shown on remote control switch). Exact manual text: "This alarm is indicated when the…

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

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