Mitsubishi Electric CITY MULTI PUHY-400YMF-B Service Handbook page 94

(17) Emergency response operating mode
The emergency operation mode is a mode in which the unit is run in an emergency to respond to the trouble when the
compressors (No. 1, No. 2) break down, making it possible to carry out a trouble reset using the remote control.
1) Starting the Emergency Operation Mode
1 Trouble occurs (Display the trouble code root and trouble code on the remote control).
2 Carry out trouble reset with the remote control.
3 If the trouble indicted in 1 above is of the kind that permits emergency operation (see the table below), initiate a
retry operation.
If the trouble indicated in 1 above is of the kind where emergency operation is impossible (see the table below),
restart operation after carrying out the previous trouble reset (without entering the emergency operation mode).
4 If the same trouble is detected again during the retry operation in 3 above, carry out trouble reset once more
with the remote control, then try emergency operation starting corresponding to the contents of the trouble.
Table Emergency Operation Mode Patterns and Trouble Codes for which Emergency Operation is Possible or Impossible
Emergency Mode Codes for which emergency operation is
Pattern possible.
When a No. 1 Serial transmission trouble
Compressor Failure VDC sensor/circuit trouble
Occurs Breaking of overcurrent
Bus voltage trouble
Radiator panel overheat
protection
Overcurrent protection
Cooling fan trouble
Thermal sensor trouble
(Radiator panel)
IDC sensor/circuit trouble
When No. 2 Overcurrent protection
Compressor Failure
Occurs
Constant capacity Error codes other than those at right.
unit
Error (stop)
Caution
During emergency operation, only × marked percentage of indoor units can be operated during emergency operation.
In case, more than × marked percentage of indoor units are operated, over than the percentage of indoor units
would be on the stand-by mode.
Failed Compressor
No.1
No.2
No. 3
External temp. (TH6)
TH6 20°C (cooling) or heating
TH6 < 20°C (cooling)
TH6 20°C (cooling) or heating
TH6 < 20°C (cooling)
Don't care
Trouble Codes for which
Emergency Operation is
Impossible
0403 Trouble codes other than
4200 those at left.
4210
4220
4230
4240
4260
5110
5301
(a)High pressure/ low-
pressure pressure
error
(b)Reverse phase error
(c)Communication error
No communication with
variable capacity unit
(d)Constant capacity unit
power-off and LEV2
open
(e)Oil equalization circuit
irregularity
Model 600 ~ 750
×
60 ~ 70 % No.2 + No.3 Compressors on
×
45 ~ 55 % No.2 Compressor only
×
65 ~ 75 % No.1 + No.3 Compressors on
×
45 ~ 55 % No.1 Compressor only
×
80 ~ 90 % No.1 + No.2 Compressors on
–91–
Action
Emergency Operation with the
No. 2 and No. 3 Compressor
* After the retry operation, even if
there is a different trouble code
detected within <Inverter
Trouble> at left, press the button
and after resetting, start the unit
by emergency operation.
[Example]
4250 → Reset → Retry → 4240
→ Reset → Emergency
operation
Emergency Operation with the
No. 1 and No. 3 Compressor
Emergency response operation
with the variable capacity unit only
1302 (No. 1 and No. 2 compressor).
4103
1559
Notes