Lennox Split & Multi-Split

Lennox Error Code P4

Split & Multi-Split

P4 means different things on different Split & Multi-Split models. Enter your model number to see only your reading, or find your model below.

What It Means

  • Compressor drive error
  • High temperature sensed at compressor discharge line.
  • MLA, MPA, MPB: Temperature protection of compressor discharge

Causes & actions from Lennox

Compressor drive error

11 models

3WMB036, M22A, M33A, M33B, MCFA, MCFB, MFMA, MMDA, MMDB, MWMA, MWMB

Mini-split unit (indoor)

How it shows
  • 507550 indoor display: P4
  • corp1816 cassette ducted floor display: P4
  • corp1816 running light: 5 times
  • corp1816 timer light: Flash
  • corp1816 wall indoor display: P4
  • Indoor receiver display: P4

Compressor drive error (Running Light: 5 times, Timer Light: Flash)

Other manual wording

M22A, M33A, M33B, MCFA, MCFB, MFMA, MMDA, MMDB

This manual entry does not list further causes or actions.

Applicable models & manual sources

High temperature sensed at compressor discharge line.

10 models

3WMB036, M22A, M33A, M33B, MCFA, MCFB, MMDA, MMDB, MWMA, MWMB

Mini-split unit (indoor)

How it shows
  • corp1816 old indoor display: P4

This manual entry does not list further causes or actions.

Applicable models & manual sources
  • MWMA

    High temperature sensed at compressor discharge line.

    MWMA, MWMB, 3WMB036, M22A, M33A, M33B, MMDA, MMDB, MCFA, MCFB

    MWMA manual, page 6

Temperature protection of compressor discharge

Models: MLA, MPA, MPB

Mini-split unit (outdoor)

How it shows
  • corp1816 multizone outdoor display: P4

This manual entry does not list further causes or actions.

Applicable models & manual sources
Disclaimer: This information is for general reference. Code wording and instructions vary by model. Always follow the service manual for your exact unit.

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