Mitsubishi Electric PUHY-HP120TNU-A, Service Handbook

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[8-9 Troubleshooting Inverter Problems ]
34
- chapter 8 HWE18240_GB
8 Troubleshooting Based on Observed Symptoms
8-9-5 Checking the Inverter for Damage during Compressor Operation
8-9-6 Checking the Fan Motor for Ground Fault and Coil Resistance Problems
Items to be checked Phenomena Remedy
Put the outdoor unit into opera-
tion.
Check the inverter output volt-
age (at the compressor terminal)
after the inverter output frequen-
cy has stabilized.
<INV42Y and INV38> 1) Overcurrent-related problems occur im-
mediately after compressor startup.
Error code : 4250
Detail code : 101, 102, 106, 107 a. Check items [8-9-2 Checking the
Inverter Board Error Detection Cir-
cuit]through [8-9-4 Checking the
Inverter for Damage at No-
Load]for problems.
b. Check that high and low pressures
are balanced.
c. Check that no liquid refrigerant is
present in the compressor and that
there is no liquid backflow.
ĺ
Go to "d." when the problem per-
sists after compressor startup was
repeated several times.
d. Check that there is a pressure dif-
ference between high and low
pressures after compressor start-
up.
ĺ
Check the high pressure 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 between
the wires after the inverter output voltage
is stabilized.
Greater than the larger of the following
values: imbalance of 5% or 5V Replace the INV board if there is a volt-
age imbalance.
Check the belt heater for problems if
there is no voltage imbalance.
ĺ
When the error occurred, liquid refrig-
erant may have been present in the
compressor.
Items to be checked Phenomena Remedy
Remove fan motor winding. Check
insulation resistance and coil resis-
tance. 1) Fan motor insulation failure.
If < 1 M
ȍ
, Defect.
Change fan motor.
2) Fan motor wire failure.
Target coil resistance: Approx. 10
ȍ
.
(Changes with temperature)
Change fan motor.