Daikin Packaged Unit

Daikin Packaged Unit Error Code LC

Troubleshooting guide for the Daikin Packaged Unit system fault LC.

ACLogics Fix Daikin code LC See how ACLogics handles it → Fix LC step-by-step

What It Means

LC is an internal communication fault between the outdoor unit's main control PCB and its inverter PCB — the two boards have lost the serial link used to command compressor speed and report inverter status — rather than a fault between separate physical units.

Possible Causes

  • Loose, damaged, or disconnected wiring harness between control PCB and inverter PCB.
  • Corroded or bent connector pins.
  • Electrical noise or poor grounding disrupting the internal serial link.
  • Defective inverter PCB communication circuit.
  • Defective control PCB communication circuit (transmission block).

Not sure which one it is — or if it's none of these? Try ACLogics today.

Disclaimer: This information is for general reference. Error codes can vary by model and production year. Always refer to your machine's specific manual and the information printed on the unit itself.
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Full Diagnosis

LC is an internal communication fault between the outdoor unit's main control PCB and its inverter PCB — the two boards have lost the serial link used to command compressor speed and report inverter status — rather than a fault between separate physical units. This sets it apart from the indoor/outdoor and remote-controller transmission codes (U4, U5, U8) and from M8/UJ, which cover communication with external centralized-control equipment or accessory devices; LC is confined to wiring or hardware between two PCBs inside the same outdoor unit cabinet. The compressor is disabled until the internal link is restored.

All Recorded Causes

Loose, damaged, or disconnected wiring harness between control PCB and inverter PCB. Corroded or bent connector pins. Electrical noise or poor grounding disrupting the internal serial link. Defective inverter PCB communication circuit. Defective control PCB communication circuit (transmission block).

Verify Before Replacing Parts

  1. Confirm the exact Daikin model family and packaged context before acting on a generic code description.
  2. Confirm board LEDs, wiring polarity, and model compatibility before replacing control boards — this Daikin fault points at loose, damaged, or disconnected wiring harness between control PCB and inverter PCB.
  3. Check for intermittent communication faults caused by connectors, moisture, or damaged harnesses, and rule out corroded or bent connector pins.
  4. After the correction, run the system long enough to confirm the packaged fault does not return under normal load.

Still unsure about this fault?

ACLogics walks you through Daikin Packaged Unit diagnostics step-by-step — so you confirm the cause before swapping parts.

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