OCH791 _43
4220 (U9): Voltage shortage/Overvoltage/PAM error/L1 open phase/
Primary current sensor error/Power synchronization sig-
nal error
Chart 2 of 2
The black square (■) indicates a switch position.
Diagnosis of failure
The bus voltage can be displayed by an operation of SW1
on the outdoor multi controller circuit board.
Continued from the previous page.
7, 8
6
ON
OFF
1 2 3 4 5 6 7 8
SW1 Setting
Display on LED1, 2
Unit
0–9999
V
Replace the noise filter circuit board.
Correct the CN5 wiring.
Replace the outdoor power circuit board
(Defective outdoor power circuit board).
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.
Check the bus voltage read by the microprocessor with
an operation of SW1 on the outdoor multi controller
circuit board.
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
Check the power supply voltage on the terminal block
of the outdoor unit.
Check the power supply facility.
Replace the outdoor power circuit board
(Defective outdoor power circuit board).
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?
Is the power supply normal?
Is the bus voltage normal?
Yes
No
No
No
No
1-phase model
3-phase model
Yes
Yes
Yes
Yes
No
