Viessmann C9

Medium

Vitocal — Safety high-pressure switch tripped, compressor off.

Viessmann C9: Safety high-pressure switch tripped, compressor off. This fault usually isn't an immediate stop, but should be checked soon.

Possible causes

Fan or primary pump faulty.
Insufficient pressure/flow in circuit.

Check steps

Check pressure & flow of both circuits, fan/pump.
Measure HP switch signal (0 V = tripped, 230 V~ = ok).

Affected parts

Sicherheitshochdruckschalter
Ventilator
Primärpumpe

Safety note

High pressure – danger; certified technician only.

Source: Viessmann resmi servis kılavuzu — Serviceanleitung WO1C, section 'C9 Kältekreis (SHD)' (p.107-108): 'Verdichter wird ausgeschaltet... Ursache: Störung Kältekreis: Sicherheitshochdruckschalter hat ausgelöst.' Matches app meaning exactly.

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

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Related fault codes

Compressor switched off, heating via alternatiA9 Low-pressure fault, compressor switches off.D3 Control high-pressure fault, compressor off.D4 Flow switch detects no flow, compressor off.D6 Utility lockout – compressor off (by energy suC5 Primary-circuit protection – compressor off.CA