Gree GUHD18ND3FO - Page 103

U-Match Series DC Inverter Service Manual
100
 E4 Discharge Protection
 E6 Communication Malfunction
Communication
malfunction
Check if the
communication wire between
indoor unit and outdoor unit is
connected well
Check if there is
open circuit in the communication
wire between indoor unit and
outdoor unit
Reconnect the
communication
wire
Replace the
communication
wire
Check if the
outdoor unit is energized
Energize the
outdoor unit
Replace the mainboard
Yes
Yes
No
No
No
Yes