Mitsubishi Electric CITY MULTI PUHY-P400YEM-A Service Handbook page 138

Check item
[5] 1Check to see if the IPM screw
Check the in-
terminal is loose.
verter circuit
2Check the exterior of the IPM.
trouble.
3Check the resistances be-
tween each terminal of IPM.
¶
Refer to [1] (5) 5) for de-
tails on IPM troubleshooting.
3) Trouble Measures when Main Power Breaker Tripped
Check item
Perform Meg check between the
terminals in the power terminal block
[1]
Tba.
Turn on the power again and check
once more.
[2]
Turn on the outdoor unit and check
that it operates normally.
[3]
Phenomena
1Screw terminal is loose.
2IPM is cracked due to swelling.
3Resistance error between each
terminal of IPM.
4All normal for items 1-3 above
Phenomena
1Zero to several ohm, or Meg
failure.
1Main power breaker trip
2No remote control display
1Operates normally without tripping
the main breaker.
2Main power breaker trip
-135-
Treatment
· Check all IPM screw terminals and tighten.
· IPM replacement
Check the operation in [3] or [4] after
replacing the IPM.
In the case of an output voltage
unbalance or error recurrence:
Replace the G/A board
In the case of an output voltage unbalance
or error recurrence after replacement:
Replace the INV board
· IPM replacement
Check the operation in [3] or [4] after
replacing the IPM.
In the case of an output voltage
unbalance or error recurrence:
Replace the G/A board
In the case of an output voltage unbalance
or error recurrence after replacement:
Replace the INV board
· IPM replacement
In the case of an output voltage unbalance
or error recurrence after replacement:
Replace the G/A board
In the case of an output voltage unbalance
or error recurrence after replacement:
Replace the INV board
Treatment
Check each part in the main inverter circuit.
Refer to "Simple checking Procedure for
individual components of main inverter
circuit".
a. Diode Stack
b. IPM
c. Rush current protection resistor
d. Electromagnetic relay
e. DC reactor
f. Noise filter
a. There is a possibility that the wiring shorted
momentarily.
Trace the short and repair.
b. If a. above is not the case, there is a
possibility that there was a compressor
failure.
· A compressor ground fault can be considered.
Go to (2)-[2].