Checking The Inverter For Damage At No-Load; Checking The Inverter For Damage During Compressor Operation - Mitsubishi Electric HP120TNU-A Service Handbook

[8-10 Troubleshooting Inverter Problems ]
8-10-4

Checking the Inverter for Damage at No-Load

Items to be checked
(1) Stop the unit.
Remove power supply.
(2) Disconnect the inverter
output wires from the
compressor terminals (U,
*1
V, W).
(3) Set SW7-1 on the MAIN
board to ON.
(4) Apply power supply.
(5) Put the outdoor unit into
operation.
Check the inverter output
voltage after the inverter
output frequency has sta-
bilized.
*1 Output voltage is present at the inverter output wiring terminal. To avoid short-circuiting and ground fault, do not let the
terminal come in contact with the unit or the compressor, and use caution not to damage the terminal.
8-10-5

Checking the Inverter for Damage during Compressor Operation

Items to be checked
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, 38>
HWE18220_GB
Phenomena
1) Inverter-related problems are detected.
2) Inverter voltage is not output at the termi-
nals (U, V, and W)
3) There is an voltage imbalance between
the wires.
Greater than 5% imbalance or 5V
4) There is no voltage imbalance between
the wires.
Phenomena
1) Overcurrent-related problems occur im-
mediately after compressor startup.
Error code : 4250
Detail code : 101, 102, 106, 107
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
Remedy
Set SW7-1 on the MAIN board to ON,
and go to [8-10-2 Checking the Invert-
er Board Error Detection Circuit].
Replace the INV board.
Replace the INV board.
Normal
*When done checking, set SW7-1 on
the MAIN board back to as it was.
Remedy
a. Check items [8-10-2 Checking the
Inverter Board Error Detection Cir-
cuit]through [8-10-4 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.
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.
Check the high pressure with
LED monitor for changes.
Replace the compressor if there is
no pressure difference. (the com-
pressor may be locked.)
Replace the INV board if there is a volt-
age imbalance.
chapter 8 -
47