What It Means
Reports an open, shorted, or out-of-range reading from the liquid-line refrigerant thermistor on the outdoor/compressor side of the circuit, used for subcooling and expansion valve control calculations.
Daikin Chiller
Daikin Chiller Error Code J8
Troubleshooting guide for the Daikin Chiller system fault J8.
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Possible Causes
- Liquid pipe thermistor lead damaged, chafed, or disconnected.
- Thermistor not properly strapped or clamped to the liquid line.
- Thermistor resistance drifted out of tolerance.
- Corroded or wet connector.
- Defective outdoor unit PCB thermistor input.
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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
Reports an open, shorted, or out-of-range reading from the liquid-line refrigerant thermistor on the outdoor/compressor side of the circuit, used for subcooling and expansion valve control calculations. It is the liquid-side counterpart to J9, which covers the equivalent fault on the gas-line thermistor, and is distinct from C4, which monitors the liquid pipe thermistor at the indoor heat exchanger rather than the outdoor refrigerant circuit. Because the liquid and gas line thermistors feed the same expansion valve control loop, check both J8 and J9 together when diagnosing erratic capacity control or nuisance trips.
All Recorded Causes
Liquid pipe thermistor lead damaged, chafed, or disconnected. Thermistor not properly strapped or clamped to the liquid line. Thermistor resistance drifted out of tolerance. Corroded or wet connector. Defective outdoor unit PCB thermistor input. Wrong thermistor substituted during a prior repair.
Verify Before Replacing Parts
- Confirm the exact Daikin model family and chiller context before acting on a generic code description.
- Verify airflow first, then confirm operating pressures and temperature relationship before adjusting charge, since liquid pipe thermistor lead damaged, chafed, or disconnected.
- Look for restrictions, iced coils, or dirty heat-transfer surfaces that can mimic a charge problem, and separately confirm thermistor not properly strapped or clamped to the liquid line.
- After the correction, run the system long enough to confirm the chiller fault does not return under normal load.
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