NTC Temp Sensor Diagnosis & Replacement — 10kΩ @25°C + B-Constant Match

Field NTC resistance test (multimeter + water/temperature)

Check: **NTC = negative-coefficient thermistor** (temp↑ → resistance↓). 10 kΩ at 25°C is Korean standard. **Field method**: disconnect sensor → multimeter ohm mode (×1K scale) → measure between leads. 10 kΩ ±5% at 25°C = OK. **Temperature accuracy check**: dip sensor tip in warm water (40°C) → confirm resistance drops (around 5–6 kΩ). No change or non-proportional = bad sensor. **B-constant** = typically B25/85 = 3950 or 3435 (manual prevails). Also check cable continuity/connector.

What to do: **Replace with same spec** (resistance, B-constant, temp range, pinout match). Mismatch = system mis-reads temp → malfunction, freezing, compressor damage. **Mount precisely**: indoor ROOM in airflow path / indoor coil inlet-outlet clips / discharge pipe with thermal grease then clip. **Cable open** = new cable or signal extension (waterproof). **Inverter PCB learning mode** = activate per manual after replacement. **Post-replace test** = run 30 min + verify indoor temp display and outdoor pressures normal.