Mitsubishi Electric City Multi PURY-EM200YNW-A1, Service Handbook

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[8-10 Troubleshooting Inverter Problems ]
BS_08_L chapter 8 -
49
8 Troub
le
sho
o
ting Bas
e
d on Ob
ser
ved
Sy
mp
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8-10-14 Checking the Pump INV Board for Damage (During pump operation)
8-10-15 Checking the Installation Conditions
8-10-16 Solutions for the Main Breaker Trip
Measure the secondary voltage of the main power breaker before checking because the main power breaker may have been
broken.
Items to be checked Phenomena Remedy
Operate the outdoor unit and the
HBC.
Wait until the inverter output frequen-
cy is stabilized, and then check the
inverter output voltage.
1) Overcurrent-related error occurs im-
mediately after the startup of the
pump or during operation of the
pump.
Check code: 4255, 4256
Detail code: 101, 102, 103, 106, 107
a. Check that the results of the
check items in [8-10-11 Checking
the Pump Motor for Ground Fault
and Coil Resistance Problems]
through [8-10-13 Checking the
Pump INV Board for Damage
(Without load)] are OK.
→ If the error persists after sever-
al compressor restarts, go to "b."
b. After the startup of the compres-
sor, check the high and low pres-
sures for a proper differential
pressure. (Water pressure)
If a proper differential pressure
does not exist, replace the pump.
(The pump may be locked.)
2) After the inverter output voltage is
stabilized, line voltage imbalance of
at least 5% or 5 V occurs.
If line voltage imbalance exists:
<INV/S20>
Replace the INV board.
Items to be checked Phenomena Remedy
(1) Check refrigerant charge. Overcharge of refrigerant Return to correct refrigerant
charge.
(2) Check outdoor unit branch in-
stallation.
The branch approach <500 mm. Make branch approach >500mm
Is the branch angle < ±15° to horizontal? Make branch angle < ±15°
Items to be checked Phenomena Remedy
[1] Check the breaker capacity. Use of a non-specified break-
er
Replace it with a specified breaker.
[2] Perform Meg check between the
terminals on the power terminal
block TB1.
Zero to several ohm, or Meg
failure
Check each part and wiring.
Refer to the following page(s). [8-10-18
Simple Check on Inverter Circuit Compo-
nents]
 IGBT module
 Rush current protection resistor
 Electromagnetic relay
 DC reactor
[3] Turn on the power again and
check again.
1) Main power breaker trip
2) No remote control display
[4] Turn on the outdoor unit and check
that it operates normally.
1) Operates normally without
tripping the main breaker.
a) The wiring may have been short-circuit-
ed. Search for the wire that short-circuit-
ed, and repair it.
b) If item a) above is not the cause of the
problem, refer to [8-10-2 Checking the
Inverter Board Error Detection Circuit] -
[8-10-10 Checking the Fan Board for
Damage with Load]
2) Main power breaker trip
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