Mitsubishi Electric PURY-P120TJMU-A, Service Handbook, Page: 323 / 411

[
IX
Troubleshooting ]
- 314 - HWE0913A GB
[4]
Check whether
the inverter is
damaged.
(During com-
pressor opera-
tion) Put the outdoor unit into oper-
ation.
Check the inverter output volt-
age after the inverter output
frequency has stabilized. 1) Overcurrent-related problems oc-
cur immediately after compressor
startup.
(4250 Details : No.101, 103, 106,
107) a. Check items [1] through
[3].
b. Check that high and low
pressures are balanced.
c. Check that no liquid re-
frigerant is present in the
compressor.
Go to "d." when the
problem persists after
compressor startup was
repeated several times.
If normal operation is re-
stored, check the belt
heater for problems.
d. Check that there is a
pressure difference be-
tween high and low
pressures after com-
pressor startup.
Check the high pres-
sure with LED monitor
for changes.
Replace the compressor
if there is no pressure
difference. (the com-
pressor may be locked.)
2) There is a voltage imbalance be-
tween the wires after the inverter
output voltage is stabilized.
Greater than the larger of the fol-
lowing values: imbalance of 5% or
5V If there is a voltage imbalance
<P72 model>
Replace the INV board.
<P96, P120, P144 models>
Replace the IPM.
If the problem persists, replace
the INV board.
If the problem persists after re-
placing the above parts, go to
section [2].
Check the belt heater for prob-
lems if there is no voltage im-
balance.
When the error occurred, liq-
uid refrigerant may have been
present in the compressor.
[5]
Check the fan
motor ground
fault or the
winding. Remove the wire for the out-
door fan motor, and check the
fan motor megger and the
winding resistance. 1) Fan motor megger failure
Failure when the megger is 1Mohm
or less. Replace the fan motor.
2) Fan motor disconnection
Standard: The winding resistance
is approximately several ohm.
(It varies depending on the temper-
ature, or while the inner thermo is
operating, it will be
ohm)
[6]
Check the FAN
board failure. (1) Check the fan output wir-
ing. Connector contact failure
Œ
Board side (CNINV)
Œ
Fan motor side
Connect the connector.
(2) Check the connector CN-
VDC connection. Cnnector contact failure Connect the connector.
(3) Check the FAN board
failure. 1) The voltage imbalance among
each motor wiring during operation
(The voltage imbalance is greater
than the larger of the values repre-
sented by 5% or 5 V.) Replace the FAN board.
2) The same error occurs even after
the operation is restarted.
Items to be checked Phenomena Remedy
[TJMU-A]