Gree GUHD09NK3FO Service Manual page 87

U-Match Series DC
Inverter Service Manual
E4 Discharge Protection
E4 protection
Check if the discharge
temperature around
compressor discharge
temperature sensor
exceeds 115
Check if there is leakage in the
system pipeline; weld the
leakage point and recharge
refrigerant after vacuum
pumping and pressure retaining
are passed
E6 Communication Malfunction
84
No
temperature sensor
Yes
Communication
malfunction
Check if the
communication wire between
indoor unit and outdoor unit is
connected well
Yes
Check if there is
open circuit in the communication
wire between indoor unit and
outdoor unit
No
Check if the
outdoor unit is energized
Yes
Replace the mainboard
No
Check if the
Yes
discharge
is normal
No
Reconnect the
communication
wire
Yes
Replace the
communication
wire
No Energize the
outdoor unit
Replace the discharge
temperature sensor
Replace the outdoor
main control board