Mitsubishi Electric City Multi CMH-WM250V-A, Service Handbook

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[8-10 Troubleshooting Inverter Problems ]
50
- chapter 8 BS_08_E
8 Troub
le
sho
oting Bas
ed on Ob
ser
ved
Sy
mp
toms
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
Items to be checked Phenomena Remedy
Operate the outdoor unit and the
hydro unit.
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: 4250
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:
<INV32>
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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