Lennox Split & Multi-Split

Lennox Error Code E434

Split & Multi-Split

E434 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

  • Outdoor control has lost communications with the inverter for greater than 3 minutes. Outdoor unit will stop all compressor demand. Outdoor control will attempt to establish communication multiple times and will automatically clear when the error clears. Unit will lock out after 60 minutes if communication is not established and will display a critical error code.
  • Outdoor control has lost communications with the inverter for greater than 3 minutes. Outdoor unit will stop all compressor demand. Outdoor control will attempt to establish communication multiple times and will automatically clear when the error clears. Unit will lock out after 60 minutes if communication is not established and will display a Service Urgent error code.

Causes & actions from Lennox

Outdoor control has lost communications with the inverter for greater than 3 minutes. Outdoor unit will stop all compressor demand. Outdoor control will attempt to establish communication multiple times and will automatically clear when the error clears. Unit will lock out after 60 minutes if communication is not established and will display a critical error code.

35 models

EL18XCV, EL18XCV-024, EL18XCV-036, EL18XCV-048, EL18XCV-060, EL18XPV, EL18XPV-024, EL18XPV-036, EL18XPV-048, EL18XPV-060, EL19KPV, EL19KPV-024, EL19KPV-036, EL19KPV-048, EL19KPV-060, EL22KCV, EL22KCV-024, EL22KCV-036, EL22KCV-048, EL22KCV-060, SL22KLV, SL22KLV-024, SL22KLV-036, SL22KLV-048, SL22KLV-060, SL25KCV, SL25KCV-024, SL25KCV-036, SL25KCV-048, SL25KCV-060, SL28XCV, SL28XCV-024, SL28XCV-036, SL28XCV-048, SL28XCV-060

Air conditioner (outdoor), Heat pump (outdoor)

How it shows
  • Inverter code: 53
  • Inverter LED flash code: Red 5 flashes, Green 3 flashes (green: flashing ×3, red: flashing ×5)
  • Outdoor control 7-segment display: E434

Issues: (1) Outdoor disconnect is off or outdoor power is off, when indoor power is on (source for 24VAC) (2) Loose electrical power connections (3) interruption of main power to the inverter (4) Generator powers indoor unit, but not the outdoor unit. Corrective Actions: (1) To reset, cycle the indoor power off (source of 24VAC to outdoor unit) and back on. This will de-energize outdoor control and inverter by cycling the contactor. (2) Make sure the disconnect is on (3) check electrical power supply connections (4) Check for proper main 230V power supply

Applicable models & manual sources
  • EL18XCV

    Outdoor control has lost communications with the inverter for greater than 3 minutes. Outdoor unit will stop all compressor demand. Outdoor control will attempt to establish communication multiple times and will automatically clear when the error clears. Unit will lock out after 60 minutes if communication is not established and will display a critical error code.

    EL18XCV, EL18XCV-024, EL18XCV-036, EL18XCV-048, EL18XCV-060

    EL18XCV manual, page 39

    EL18XCV manual, page 78

    EL18XCV manual, page 78

  • EL18XPV

    Outdoor control has lost communications with the inverter for greater than 3 minutes. Outdoor unit will stop all compressor demand. Outdoor control will attempt to establish communication multiple times and will automatically clear when the error clears. Unit will lock out after 60 minutes if communication is not established and will display a critical error code.

    EL18XPV, EL18XPV-024, EL18XPV-036, EL18XPV-048, EL18XPV-060

    EL18XPV manual, page 39

    EL18XPV manual, page 81

    EL18XPV manual, page 81

  • EL19KPV

    Outdoor control has lost communications with the inverter for greater than 3 minutes. Outdoor unit will stop all compressor demand. Outdoor control will attempt to establish communication multiple times and will automatically clear when the error clears. Unit will lock out after 60 minutes if communication is not established and will display a critical error code.

    EL19KPV, EL19KPV-024, EL19KPV-036, EL19KPV-048, EL19KPV-060

    EL19KPV manual, page 45

    EL19KPV manual, page 45

  • EL19KPV

    Outdoor control has lost communications with the inverter for greater than 3 minutes. Outdoor unit will stop all compressor demand. Outdoor control will attempt to establish communication multiple times and will automatically clear when the error clears. Unit will lock out after 60 minutes if communication is not established and will display a critical error code.

    EL19KPV, EL19KPV-024, EL19KPV-036, EL19KPV-048, EL19KPV-060

    EL19KPV manual, page 82

    EL19KPV manual, page 82

  • EL22KCV

    Outdoor control has lost communications with the inverter for greater than 3 minutes. Outdoor unit will stop all compressor demand. Outdoor control will attempt to establish communication multiple times and will automatically clear when the error clears. Unit will lock out after 60 minutes if communication is not established and will display a critical error code.

    EL22KCV, EL22KCV-024, EL22KCV-036, EL22KCV-048, EL22KCV-060

    EL22KCV manual, page 42

    EL22KCV manual, page 42

    EL22KCV manual, page 78

  • SL22KLV

    Outdoor control has lost communications with the inverter for greater than 3 minutes. Outdoor unit will stop all compressor demand. Outdoor control will attempt to establish communication multiple times and will automatically clear when the error clears. Unit will lock out after 60 minutes if communication is not established and will display a critical error code.

    SL22KLV, SL22KLV-024, SL22KLV-036, SL22KLV-048, SL22KLV-060

    SL22KLV manual, page 45

  • SL22KLV

    Outdoor control has lost communications with the inverter for greater than 3 minutes. Outdoor unit will stop all compressor demand. Outdoor control will attempt to establish communication multiple times and will automatically clear when the error clears. Unit will lock out after 60 minutes if communication is not established and will display a critical error code.

    SL22KLV, SL22KLV-024, SL22KLV-036, SL22KLV-048, SL22KLV-060

    SL22KLV manual, page 88

  • SL25KCV

    Outdoor control has lost communications with the inverter for greater than 3 minutes. Outdoor unit will stop all compressor demand. Outdoor control will attempt to establish communication multiple times and will automatically clear when the error clears. Unit will lock out after 60 minutes if communication is not established and will display a critical error code.

    SL25KCV, SL25KCV-024, SL25KCV-036, SL25KCV-048, SL25KCV-060

    SL25KCV manual, page 39

    SL25KCV manual, page 39

    SL25KCV manual, page 73

    SL25KCV manual, page 73

  • SL28XCV

    Outdoor control has lost communications with the inverter for greater than 3 minutes. Outdoor unit will stop all compressor demand. Outdoor control will attempt to establish communication multiple times and will automatically clear when the error clears. Unit will lock out after 60 minutes if communication is not established and will display a critical error code.

    SL28XCV, SL28XCV-024, SL28XCV-036, SL28XCV-048, SL28XCV-060

    SL28XCV manual, page 33

    SL28XCV manual, page 67

Outdoor control has lost communications with the inverter for greater than 3 minutes. Outdoor unit will stop all compressor demand. Outdoor control will attempt to establish communication multiple times and will automatically clear when the error clears. Unit will lock out after 60 minutes if communication is not established and will display a Service Urgent error code.

5 models

EL21KLV, EL21KLV-024, EL21KLV-036, EL21KLV-048, EL21KLV-060

Heat pump (outdoor)

How it shows
  • Inverter code: 53
  • Inverter LED flash code: Red 5 flashes, Green 3 flashes (green: flashing ×3, red: flashing ×5)
  • Outdoor control 7-segment display: E434

Issues: (1) Outdoor disconnect is off or outdoor power is off, when indoor power is on (source for 24VAC) (2) Loose electrical power connections (3) interruption of main power to the inverter (4) Generator powers indoor unit, but not the outdoor unit. Corrective Actions: (1) To reset, cycle the indoor power off (source of 24VAC to outdoor unit) and back on. This will de-energize outdoor control and inverter by cycling the contactor. (2) Make sure the disconnect is on (3) check electrical power supply connections (4) Check for proper main 230V power supply

Applicable models & manual sources
  • EL21KLV

    Outdoor control has lost communications with the inverter for greater than 3 minutes. Outdoor unit will stop all compressor demand. Outdoor control will attempt to establish communication multiple times and will automatically clear when the error clears. Unit will lock out after 60 minutes if communication is not established and will display a Service Urgent error code.

    EL21KLV, EL21KLV-024, EL21KLV-036, EL21KLV-048, EL21KLV-060

    EL21KLV manual, page 48

    EL21KLV manual, page 94

    EL21KLV manual, page 94

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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