GREE GMV5E DC INVERTER VRF UNITS SERVICE MANUAL
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causes phase loss or reverse), it will report this error
Possible reason
：
■The power supply connected to the unit is incorrect, phase loss or reverse happens
■Detecting circuit is abnormal
Troubleshooting:
2.2.4.134
“U4” Lack of refrigerant protection
Error display:
ODU mainboard, IDU wired controller and IDU receive light board will
display
Error judgment condition and method:
Check the system high pressure and low pressure through pressure sensor. When the system high
pressure and low pressure is lower than 5 of outdoor ambient temperature before starting operation, the
unit will stop for protection.
Possible reason
：
■Refrigerant charging amount is insufficient;
■System pipeline is leaked;
Troubleshooting:
2.2.4.135
“U6” Valve error
Error display:
ODU mainboard, IDU wired controller and IDU receive light board will
display
