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LG Therma V fault CH52

Communication error inv PCB(outdoor) ↔ main PCB(outdoor cycle)

Heat pump

What it means

Failure to receive wired Inv PCB(Outdoor) signal in Main PCB(Outdoor Cycle), indicating a communication breakdown between the inverter PCB and main outdoor cycle PCB.

Likely causes

  1. Communication line connection failure
  2. Harness of communication line failure
  3. Abnormal refrigerant pressure
  4. Compressor wiring reverse phase loss
  5. Inverter PCB assembly or connector connection fault
  6. Communication line shorted or disconnected
  7. Main PCB(Indoor) CN-REMO voltage not present (fault on Main PCB)
  8. Noise near wired remote control or communication line

Where to start

  1. Visually inspect the yellow LED on Main PCB(Outdoor Cycle) for normal blinking.
  2. Locate the EEPROM Vcc and GND points on the Main PCB(Outdoor Cycle).
  3. Compare measured voltage against 5V threshold to determine if Main PCB replacement is needed.

The full answer, free

  • 15 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 117), right under the answer
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Safety: Isolate the outdoor unit and any backup heater, and give the inverter capacitors time to discharge before you open the electrics. Anything on the refrigerant circuit needs F-gas certification.

From the LG manual for the Therma V. Check the model on the data plate before you order parts.

Other LG Therma V fault codes