Mitsubishi Electric MXZ-SM36NAM2 Technical & Service Manual page 77

Check code
Voltage shortage/overvoltage/PAM error/L1 open phase/primary
4220
(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
Is the outdoor unit
single-phase or 3-phase?
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.
Is the power supply normal?
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
below on the outdoor power circuit board
using a multimeter.
Test points: CNDC 1-3 pin
Is the bus voltage normal?
OCH810A
current sensor error/power synchronization signal error
Diagnosis
6
3-phase
Yes
No
Yes
Yes
The black square (■) indicates a switch position.
Replace the outdoor power circuit board
Single-phase
(Defective outdoor power circuit board).
No
Replace the noise filter circuit board.
Yes
Replace the outdoor power circuit board
(Defective outdoor power circuit board).
No 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
ON
0–9999
OFF
1 2 3 4 5 6 7 8
Check the resistor connected to 52C relay
and reactor. Replace it if the resistor is
No
broken. Replace the outdoor power circuit
board if the resistor is not broken.
Operate the unit and check if the problem
occurs again.
77
Chart 2 of 2
Remedy
Correct the CN5 wiring.
Unit
V