Mitsubishi Electric MXZ-SM72TAM-U1 Service Manual page 57

4250 (U6): Power module trouble
Abnormal points and detection methods
Both of the following conditions have been satisfied:
• Overcurrent of DC bus or compressor is detected during
compressor operation.
• Inverter power module is determined to be faulty.
Diagnosis of failure
Turn the power OFF to check for looseness or
disconnection of the compressor wiring.
Is it connected properly?
1. Disconnect the compressor wiring (U-V-W
phase).
2. Turn ON the SW7-1(*) on the outdoor multi
controller circuit board.
3. Operate the unit.
Is error code 4250 still displayed?
* SW7-1 ON: Ignore 5300(UH) error.
OCH800A_57
No
Yes
No
Yes
Causes and checkpoints
• Short-circuit caused by looseness or disconnection of
compressor wiring
• Defective compressor
• Defective outdoor power circuit board
Connect the compressor wiring (U, V and W
phase) properly, then turn the power back ON.
Replace the compressor
(Defective compressor).
Replace the outdoor power circuit board or the
outdoor multi controller circuit board
(Defective outdoor power circuit board).