Mitsubishi Electric City Multi PQHY-P72 Service Handbook page 202

Error definition and error
Error Code
4220 Bus voltage If Vdc 150V or less is de-
drop tected during Inverter op-
(Detail code eration. (S/W detection)
108)
If Vdc 425V or more is
Bus voltage rise
(Detail code 109)
detected during inverter
operation.
Abnormal VDC Bus voltage abnormality If Vdc
(Detail code 110) 400V or more or Vdc 160V or
less is detected. (H/W detec-
tion)
Refer to section -7-"Inverter " under part [4] "Trouble shooting principal parts" for error codes related to the inverter.
detection method
(1) Power supply environment
(2) Voltage drop detected
(3) Main board failure
(4) 52C failure
(5) Diode stack failure
(1) Different voltage connection
(2) INV board failure
Same as detail code No.108
and 109 of 4220 error
- 193 -
Cause Check method and remedy
Check whether the unit makes an instanta-
neous stop when the detection result is ab-
normal or a power failure occurs.
Check whether the power voltage is 150V or
less across all phases.
Measure voltages of the male con-
nector (CNDC2) on the compressor
INV board.
-> Replace the INV board when
there is no voltage drop.
-> Check the followings when
there is a voltage drop.
1) Check the voltage of CN52C on
the main board.
Refer to (3).
2) Check whether 52C works normally
Refer to (4).
Or check 52C connecting piping.
3) Check for the diode stack.
Refer to (5).
4) Check for the wiring and the con-
nectors between the CNDC2-G
on the compressor INV board
and the CNDC1 on the G/A
board.
Replace G/A board when no fault is
found for the above (1) - (4).
Check whether AC208/230V is applied to
the male connector (CN52C) on the main
board during inverter operation.
->If not applied, check the main board
and the fuse (F1 andF2).
Replace the main board when no
fault is found.
Refer to 9.[4].-7-.(4) and check the
coil resistance check.
Refer to 9 .[4].-7-.(6) and check the
diode stack resistance.
Check the power supply voltage on the pow-
er supply terminal block (TB1).
If no problems are found with the power
supply, replace the compressor INV board.
Same as detail code No.108 and
109 of 4220 error.
[ IX Troubleshooting ]