Lennox P1

Medium

Mini-Split MWM/MPA (Außeneinheit) — High pressure switch open — trips at 639 PSI and resets at 464 PSI.

Lennox P1: High pressure switch open — trips at 639 PSI and resets at 464 PSI. This fault usually isn't an immediate stop, but should be checked soon.

Possible causes

Condenser poor airflow, refrigerant overcharge, or fan failure.

Check steps

Clean condenser, check fan, verify charge.

Affected parts

Hochdruckschalter

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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