Mitsubishi Electric MXZ-SM72TAM-U1 Service Manual page 50

4100 (UF): Compressor current interruption (Locked compressor)
Abnormal points and detection methods
Overcurrent of DC bus or compressor is detected within 30
seconds after the compressor starts the operation.
Diagnosis of failure
Check the stop valve.
Is the stop valve (liquid/gas) fully
open?
Check the power supply voltage.
Is the power supply voltage normal?
Check if the model selection switches are set
correctly on the indoor controller board or
outdoor multi controller circuit board.
Are they set properly?
Turn the power OFF to check for looseness,
disconnection, or wrong phase of compressor
wiring connection.
Continue to the next page.
OCH800A_50
No
Yes
No
Yes
No
Yes
Causes and checkpoints
• Closed stop valve
• Decrease of power supply voltage
• Looseness, disconnection, or wrong phase of compres-
sor wiring connection
• Incorrect DIP-SW setting of model selection on the
outdoor controller board
• Defective compressor
• Defective outdoor power circuit board
Open the stop valve (liquid/gas) fully.
• Check the looseness, disconnection, or
breakage of compressor wiring.
• Ensure power supply from the facility.
(Check for power supply open phase.)
Set the model selection switches correctly, then
restart.
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