Mitsubishi Electric City Multi PQHY-P72 Service Handbook page 236

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)
Bus voltage If Vdc 425V or more is
rise detected during inverter
(Detail code operation.
109)
Abnormal VDC Bus voltage abnormality If
Vdc 400V or more or Vdc
(Detail code
160V or less is detected.
110)
(H/W detection)
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 connec-
tion
(2) INV board failure
Same as detail code No.108
and 109 of 4220 error.
- 227 -
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 connec-
tor (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 nor-
mally.
Refer to (4) or check 52C con-
necting piping.
3) Check for the diode stack.
Refer to (5).
4) Check the wiring and the connectors
between the CNDC2-G on the com-
pressor 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 / 230 V is ap-
plied to the male connector (CN52C)
on the main board during inverter oper-
ation.
-> If not applied, check the main board
and the fuse (F01 andF02). Re-
place 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
power 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 ]