Mitsubishi Electric CITY MULTI PUMY-P112VKM6 Service Manual page 52

4220 (U9): Voltage shortage/Overvoltage/PAM error/L1 open phase/
Diagnosis of failure
Continued from the previous page.
7, 8
Is the outdoor unit 1-phase model or
3-phase model?
Is CN5 connected properly without
any contact failure?
Is there any breakage of ACCT on the
noise filter circuit board?
Check the power supply voltage on the terminal block
of the outdoor unit.
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
multimeter.
single phase model: CNDC 1-2pin
three phase model: N2-P2
Is the bus voltage normal?
OCH790 _52
Primary current sensor error/Power synchronization sig-
nal error
6
1-phase model
3-phase model
No
Yes
Yes
No
No
Yes
No
Yes
No
Yes
Replace the outdoor power circuit board
(Defective outdoor power circuit board).
Correct the CN5 wiring.
Replace the noise filter circuit board.
Replace the outdoor power circuit board
(Defective outdoor power circuit board).
Check the power supply facility.
The bus voltage can be displayed by an operation of SW1
on the outdoor multi controller circuit board.
SW1 Setting Display on LED1, 2 Unit
ON
0–9999 V
OFF
1 2 3 4 5 6 7 8
Check the power supply facility.
Check the resistor connected to 52C relay and
reactor.
Replace it if the resistor is broken.
Replace the outdoor power circuit board if the
resistor is not broken.
Operate the unit and check if the problem occurs
again.
The black square (■) indicates a switch position.
Chart 2 of 2