Lennox P2

Critical

Mini-Split MWM/MPA (Außeneinheit) — Low pressure switch open — trips at 20 PSI and resets at 43 PSI.

Lennox P2: Low pressure switch open — trips at 20 PSI and resets at 43 PSI. This fault typically halts operation and needs immediate attention.

Possible causes

Low refrigerant charge, liquid line restriction, or low evaporator airflow.

Check steps

Check refrigerant charge, liquid line, and air filter.

Affected parts

Niederdruckschalter

Safety note

Refrigerant under pressure — use PPE.

Source: Lennox Mini-Split Systems Service Manual — Indoor and Outdoor Unit Error Codes (Corp. 1816-L7, 2018), "Extended Reference Guide - Outdoor Unit Error Codes" §4 and "Indoor Unit Error Codes" §5

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

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Related fault codes

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