P9 Coil sensor TH5 open or shorted

What the control is telling you

The condenser/evaporator thermistor TH5 reads 90°C or more, or -40°C or less, and does not recover after 3 minutes. 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

• TH5 thermistor out of range
• Loose connector CN44 on the indoor control board
• Broken wire in the thermistor lead
• Refrigerant circuit problem driving the coil 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 TH5 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. In test mode, read the coil temperature on the remote. Extreme readings with a good sensor point to a refrigerant problem.
5. If nothing above is wrong, replace the indoor board.
6. After the repair, cycle the power and run the unit to confirm the code does not come back.

Models that show this code

14 models in Mr. Slim PEAD-RP JA(L) ducted indoor unit

Other codes on the same units

• P1 Room (intake) air sensor TH1 open or shorted
• P2 Liquid pipe sensor TH2 open or shorted
• P4 Drain float switch disconnected
• P5 Drain overflow - float switch wet with pump running
• P6 Coil freeze or overheat protection
• P8 Pipe temperature out of range (coil not cooling or heating)
• Fb Indoor control board memory error
• PA Water leak detected