Mitsubishi Electric PURY-P72 Service Handbook page 148

[ VII Control ]
-11- Emergency Operation Mode
1. Problems with the outdoor unit
The P144 through P240 models of unit have a mode that allows the outdoor unit to perform an emergency 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
Compressor
Fan motor
Inverter
TH2
TH3
TH4
Thermistor
TH5
TH6
TH7
Power
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.
(2) Ending the emergency operation
1) End conditions
When one of the following conditions is met, emergency operation stops, and the unit makes an error stop.
When the integrated operation time of compressor in cooling mode has reached four hours.
When the integrated operation time of compressor in heating mode has reached two hours.
When an error is detected that does not permit the unit to perform an emergency operation.
2) Control at or after the completion of emergency operation
At or after the completion of emergency operation, the compressor stops, and the error code reappears on the remote con-
troller.
If another error reset is performed at the completion of an emergency mode, the unit repeats the procedures in section (1)
above.
To stop the emergency mode and perform a current-carrying operation after correcting the error, perform a power reset.
HWE0803A
Error codes that permit an
emergency operation
0403 Serial communication error
4220, 4225 Bus voltage drop
4230 Heatsink overheat protection
4240 Overload protection
4250, 4255 Overcurrent relay trip
5110 Heatsink temperature sensor failure (THHS)
5301 Current sensor/circuit failure
5102 Subcool heat exchanger bypass outlet temperature sensor failure
5103 Pipe temperature sensor failure
5104 Discharge temperature sensor failure
5105 Accumulator inlet temperature sensor failure
5106 Subcool heat exchanger liquid outlet sensor failure
5107 Outside air temperature sensor failure
4102 Open phase
4115 Power supply sync signal abnormality
OC failure
pattern
Trouble
OC
Normal
OS
Cooling
Permitted Permitted
Emergency
operation
Heating
Permitted Permitted
Maximum total capacity
of indoor units (Note 1)
- 139 -
Error code description
OS failure
pattern
Normal
Trouble
60%
GB