Mitsubishi Electric PUHY-HP144TSHMU-A Service Handbook page 209

[ IX 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 unit and check
that it operates normally.
HWE0716A
Phenomena
Zero to several ohm, or Meg failure Check each part in the main inverter
1) Main power breaker trip
2) No remote control display
1) Operates normally without tripping
the main breaker.
2) Main power breaker trip
- 200 -
Remedy
circuit.
*Refer to "Simple checking Proce-
dures for individual components of
main inverter circuit".
Diode stack
IPM
Rush current protection resistor
Electromagnetic relay
DC reactor
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].
GB