Midea ATOM B Series Service Manual page 54

2.5 E4: Temperature sensor (T3/T4) fault (For all models)
2.5.1 Digital display output
E4
2.5.2 Description
 Outdoor heat exchanger temperature sensor (T3) error or outdoor ambient temperature sensor (T4) error.
 The system stops running.
 Error code is displayed on the outdoor unit PCB.
2.5.3 Trigger / recover condition
 Trigger condition: The main control board cannot receive the feedback signal of temperature sensor T3 or T4.
 Recover condition: The main control board can receive the feedback signal of temperature sensor T3 or T4.
 Reset method: Resume automatically.
2.5.4 Possible causes
 Temperature sensor not connected properly or has malfunctioned.
 Temperature sensor port connect to the main board connecter is loose.
 Damaged main PCB.
2.5.5 Procedure
Temperature sensor connection on main
Temperature sensor has short-circuited
Replace outdoor main PCB
Notes:
1. Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not consistent with the sensor's resistance
characteristics table, the sensor has failed.
E4
PCB is loose
No
1
or failed
No
Atom B Series VRF 50/60Hz
Yes
Ensure the sensor is connected properly
Yes
Replace the sensor
53