Emergency Operation Mode - Mitsubishi Electric HP120TNU-A Service Handbook

[5-2 Outdoor Unit Control ]
5-2-15

Emergency Operation Mode

1. Problems with the outdoor unit
Systems with two outdoor units have a mode that allows one of the outdoor units to perform a backup operation when the
other outdoor unit in the system malfunctions.
This mode can be started by performing an error reset via the remote controller.
(1) Starting the emergency operation
1) When an error occurs, the error source and the error code will be displayed on the display on the remote controller.
2) The error is reset using the remote controller.
3) If an error code appears that permits an emergency operation in step 1) above, (See the table below.), the retry operation
starts.
4) If the same error is detected during the retry operation (step 3 above), an emergency operation can be started by resetting
the error via the remote controller.
Error codes that permit an emergency operation (Applicable to both OC and OS)
Trouble source
0403
4220,4225,4226
4230,4235
Compressor 4240,4245
Fan motor
Inverter 4250,4255,4256
5110
5301
5305,5306
Thermistor TH3 5103
TH4 5104
TH5 5105
TH7 5107
TH15 5115
Power 4102
4115
Emergency operation pattern (2 outdoor units)
1) If an attempt is made to put into operation a group of indoor units whose total capacity exceeds the maximum allowable ca-
pacity, some of the indoor units will go into the same condition as Thermo-OFF.
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Error codes that permit an
emergency operation
Serial communication error
Bus voltage drop
Heatsink overheat protection
Overload protection
Overcurrent relay trip
Heatsink temperature sensor failure (THHS)
Current sensor/circuit failure
Position error
Pipe temperature sensor failure
Discharge temperature sensor failure
Accumulator inlet temperature sensor failure
Outside air temperature sensor failure
Compressor shell bottom temperature sensor fault
Open phase
Power supply sync signal abnormality
OC
OS
Cooling
Emergency
operation
Heating
Maximum total capacity
of indoor units (Note 1)
Error code description
OC failure OS failure
pattern pattern
Trouble Normal
Normal Trouble
Permitted Permitted
Permitted Permitted
60%
HWE18220_GB