Mitsubishi Electric PUHY-HP120TNU-A, Service Handbook, Page: 230 / 324

[8-9 Troubleshooting Inverter Problems ]
HWE18240_GB chapter 8 -
33
8 Troubleshooting Based on Observed Symptoms
8-9-2 Checking the Inverter Board Error Detection Circuit
*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.
8-9-3 Checking the Compressor for Ground Fault and Coil Resistance Problems
8-9-4 Checking the Inverter for Damage at No-Load
*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.
Items to be checked Phenomena Remedy
(1) Stop the unit.
Remove power supply. 1) Overcurrent error
Error code: 4250
Detail code: No. 101, 104, 105, 106, and
107 Replace the INV board.
(2) Disconnect the inverter
output wires from the
compressor terminals (U,
V, W).
*1
2) Logic error
Error code: 4220
Detail code: No. 111 Replace the INV board.
(3) Apply power supply. 3) ACCT sensor circuit failure
Error code: 5301
Detail code: No.117 Replace the INV board.
(4) Put the outdoor unit into
operation. 4) IPM open
Error code: 5301
Detail code: No.119 Normal
Items to be checked Phenomena Remedy
Disconnect the compressor wir-
ing, and check the compressor
Meg, and coil resistance. 1) Compressor Meg failure
Error if less than 1 M
ȍ
.
Check that there is no liquid refrigerant
in the compressor.
If there is none, replace the compres-
sor.
2) Compressor coil resistance failure
Coil resistance value
HP72 model
0.078
ȍ
(YNU), 0.192
ȍ
(TNU)
HP96, 120 models
0.087
ȍ
(YNU), 0.219
ȍ
(TNU)
Replace the compressor.
Items to be checked Phenomena Remedy
(1) Stop the unit.
Remove power supply. 1) Inverter-related problems are detected. Set SW7-1 on the MAIN board to ON,
and go to [8-9-2 Checking the Inverter
Board Error Detection Circuit].
(2) Disconnect the inverter
output wires from the
compressor terminals (U,
V, W).
*1
2) Inverter voltage is not output at the termi-
nals (U, V, and W) Replace the INV board.
(3) Set SW7-1 on the MAIN
board to ON. 3) There is an voltage imbalance between
the wires.
Greater than 5% imbalance or 5V Replace the INV board.
(4) Apply power supply.
(5) Put the outdoor unit into
operation.
Check the inverter output
voltage after the inverter
output frequency has sta-
bilized. 4) There is no voltage imbalance between
the wires. Normal
*When done checking, set SW7-1 on
the MAIN board back to as it was.