Midea M-Thermal Arctic HT R290 Mono fault E9

What it means

Fault relating to the Th return-air temperature sensor.

Likely causes

1. Loose, misconnected, broken or moisturized sensor connection
2. Sensor short-circuit (resistance < 0.5 kΩ)
3. Sensor failure (resistance > 380 kΩ)
4. Resistance inconsistent with resistance characteristics table
5. Sensor probe dislodged from installation position
6. Main Control PCB failure
7. Sensor fault or wiring fault at CN5 port
8. Water temperature sensor resistance does not match expected characteristics table value
9. Set temperature reached

Where to start

1. Step 1: Check if temperature sensor connection on Main Control PCB is loose, misconnected, broken or moisturized. If yes, reconnect the temperature sensor correctly and keep it dry.
2. Step 2: If connection is fine, pull out the temperature sensor and measure sensor resistance. If resistance is too low (<0.5 kΩ), sensor has short-circuited. If resistance is too high (>380 kΩ), sensor has failed. Compare to the resistance characteristics table in Part 4 Appendix; if inconsistent, sensor has failed. Replace the sensor if so.
3. Step 3: If resistance test is normal, check fixed position of sensor and whether sensor probe has fallen off. If yes, re-fix the sensor firmly to the installation position.