P2 Liquid pipe sensor TH2 open or shorted

What the control is telling you

The liquid-line thermistor TH2 reads 90°C or more, or -40°C or less, and does not recover after the 3-minute pause. Checked in cool, dry and heat (not during defrost).

Applies to: PEAD-RP35/50/60/71/100/125/140JA and JA(L) ducted indoor units (220-240 V models)

Likely causes

• TH2 thermistor out of range
• Loose connector CN44 on the indoor control board
• Broken wire in the thermistor lead
• Refrigerant circuit problem driving the pipe temperature to an extreme
• Faulty indoor control board

Test and repair steps

1. Turn the unit off at the remote first, then switch off the breaker before opening the unit or unplugging connectors.
2. Unplug TH2 at CN44 and measure it. Thermistor values (approx.): 0°C 15 kΩ, 10°C 9.6 kΩ, 20°C 6.3 kΩ, 25°C 5.2 kΩ, 30°C 4.3 kΩ, 40°C 3.0 kΩ. Open or short = bad sensor.
3. Reseat CN44 and retry.
4. Run the unit in test mode and read the liquid pipe temperature on the remote. Very low in cooling or very high in heating means a refrigerant circuit problem, not the sensor.
5. If the displayed pipe temperature is far from the real pipe temperature with a good sensor, replace the indoor board.
6. After the repair, cycle the power and run the unit to confirm the code does not come back.