Mitsubishi Electric PUMY-P36NKMU2-BS Technical & Service Manual page 70

Check code
4220
Primary current sensor error/Power synchronization signal error
(U9)
●Diagnosis of defects
Make sure to turn the power OFF before connecting/disconnecting
any connectors, or replacing boards.
Continued from the previous page.
7,8
Check the bus voltage read by the microprocessor
with an operation of SW1 on the outdoor multi
controller circuit board.
Is the power supply normal?
Check the bus voltage at the test points
listed below on the outdoor power circuit
board using a tester.
CNDC 1-2pin
Is the bus voltage normal?
The difference of the voltage between the
one read by the LED1 and 2, and the one at
the test points listed above is large.
OCH695B
Voltage shortage/Overvoltage/PAM error/L1 open-phase/
Diagnosis
6
Yes
Yes
Yes
No
The black square (■) indicates a switch position.
Replace the outdoor power circuit board
(Defective outdoor power circuit board).
The bus voltage can be displayed by an
operation of SW1 on the outdoor multi
controller circuit board.
SW1 Setting
Display on LED1,2
ON
0–999.9
OFF
1 2 3 4 5 6 7 8
• Decrease of power supply voltage
No
• L1 open-phase
Replace the outdoor power circuit board
No
(Defective outdoor power circuit board).
Replace the outdoor power circuit board
(Trouble of an input current detection
Yes
circuit is suspected).
Check the power supply facility
(Check if a receiving electricity is lowered).
70
Chart 2 of 2
Remedy
Unit
V