Gree U-MATCH Series Service Manual page 88

 E3 stands for three statuses:
(1) Low pressure protection;
(2) Refrigerant lacking protection;
(3) Refrigerant recycling mode;
1) If enter refrigerant recycling mode through special operation, the displayed E3 is not an error
code. It will be eliminated when exiting refrigerant recycling mode.
2) If you do not want to have refrigerant lacking protection, you can enter the debugging mode
through wired controller and then cancel the refrigerant lacking protection mode.
U-Match Series DC Inverter Service Manual
85