Mitsubishi Electric City Multi PQHY-P72 Service Handbook page 301

[ IX Troubleshooting ]
[5] Check whether the IPM screw
Check the in- terminal is not loose.
verter circuit
Check the exterior of the IPM.
trouble.
Check the resistances between
each terminal of IPM.
Refer to 9.[4].5.(5) for details on
IPM troubleshooting.
(3) Trouble treatment when the main power breaker is tripped.
Items to be checked
[1] Perform Meg check between the
terminals on the power terminal
block TB1.
[2] Turn on the power again and
check again.
[3] Turn on the outdoor(heat source)
unit and check that it operates nor-
mally.
Items to be checked
1) Terminal screws are
2) IPM is cracked due to
3) Check the resistances
4) All normal for items 1) - 3)
Phenomena
Zero to several ohm, or Meg failure Check each part in the main inverter cir-
1) Main power breaker trip
2) No remote control display
1) Operates normally without trip-
ping the main breaker.
2) Main power breaker trip
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Phenomena
Check for loose IPM terminal
loose. screws and tighten them.
Replace the IPM. Check the oper-
swelling. ation in [3] or [4] after replacing the
IPM.
In the case of an output voltage im-
balance or error reoccurrence: Re-
place the G/A board.
In the case of an output voltage
imbalance or error reoccur-
rence after replacement:
Replace the INV board.
Replace the IPM.Check the opera-
between each terminal of tion in [3] or [4] after replacing the
IPM. IPM.
In the case of an output voltage im-
balance or error reoccurrence: Re-
place the G/A board.In the case of
an output voltage imbalance or er-
ror reoccurrence after replace-
ment:
Replace the INV board.
Replace the IPM.
above. In the case of an output voltage im-
balance or error reoccurrence:
Replace the G/A board.In the case
of an output voltage imbalance or
error reoccurrence after replace-
ment:
Replace the INV board.
cuit.
*Refer to "Simple checking Procedures
for individual components of main in-
verter circuit".
Diode stack
IPM
Rush current protection resistor
Electromagnetic relay
DC reactor
Noise filter
a) The wiring may have been short-
circuited. Search for the wire
that short-circuited, and repair it.
b) If item a) above is not the cause
of the problem, the compressor
may have a problem.
A compressor ground fault can be con-
sidered. Go to (2)-[2].
Remedy
Remedy