32
LED2
LED indication for communication status
Communication status is indicated by the LED.
Unit status
No
Blinking: normal communication
Lighted: abnormal communication or not connected
s
e
Y
Not lighted: The outdoor P.C. board is abnormal.
NOTE: "Lit" and "Not lit" in the table below
does not indicate abnormal.
Outdoor display P.C. board
o
N
o
N
LED 1
LED 2
Unit A
Unit B
status
status
Yes
o
N
s
e
Y
s
e
Y
No
Yes
No
(Lit or
not lit)
*1 Turn OFF the power supply before replacing
the indoor P.C. board.
Refer to indoor unit service manual.
*2 The LED indicates the status of serial
communication.
Check the communication status.
*3 Turn OFF the power supply before replacing
the inverter P.C. board.
Be careful of residual voltage of smoothing capacitor.
*4 Remove the bridge between outdoor terminal block
S2 and S3. Connect the indoor/outdoor connecting wire.
Turn ON the power supply.
Is there rated voltage
between outdoor
terminal block S1 and S2?
Check the power supply
and correct the problem.
Press the EMERGENCY
OPERATION switch
once.
Does the OPERATION
INDICATOR lamp light
up? <Confirmation of
the power to the indoor
unit>
Is there rated
voltage between
outdoor terminal
block S1 and S2?
Check the indoor/outdoor
connecting wire and
correct the problem.
Replace the indoor
electronic control
P.C. board. *1
Is serial signal error
indicated 6 minutes
later?
Is there any miswiring,
poor contact, or wire
disconnection of the
indoor/outdoor
connecting wire?
Check the indoor/outdoor
connecting wire and
correct the problem.
Turn OFF the power supply.
Turn ON the power supply.
Does the LED on the
outdoor display P.C.
board or the outdoor control
P.C. board repeat quick
BLINKING and OFF? *2
Replace the inverter P.C.
board. *3 *4
If the trouble sometimes occurs,
possible causes are as follows:
• Poor connection of the indoor/
outdoor connecting wire
Check for intermediate connection of
the indoor/outdoor connecting wire,
loose connection to the terminal block,
and cut wire inside the cable.
If any of them is found, correct the
problem(s).
• Effects of the inverter lighting
on the indoor unit
If the trouble occurs or does not occur
depending on whether the light is on
or off, distance the lighting from the
indoor unit or apply the glass filter on
the receiving part of the indoor unit.
• Noise on the indoor/outdoor
connecting wire
Pass the indoor/outdoor connecting
wire through a different route if the
existing wiring is arranged as below:
• The indoor/outdoor connecting wire
runs near the power supply cable of
other equipment.
• The indoor/outdoor connecting wire
is detoured and run long.
Remove the
indoor/outdoor connecting
wire from the outdoor
terminal block connected
with the indoor unit on
which miswiring or the
serial signal error is
indicated. Bridge between
S2 and S3 of the outdoor
terminal block.
Yes
Yes
Yes
LED1
Lit
Not lit
Replace the indoor
power P.C. board.*1
Is there amplitude of 10 to 20 V DC
between the indoor terminal block
S2 and S3? <Confirmation of serial signal>
Check the wiring.
If there are any errors of the
indoor/outdoor connecting wire:
such as the damage of the wire,
intermediate connection, and/
or poor contact to the terminal
block, replace the indoor/
outdoor connecting wire.
No
Is there 2 V DC or less between CN10A (+)
and GND on the indoor electronic control
P.C. board?
No
Yes
Is there 2 V DC or less
between CN10A (+) and
GND on the indoor
electronic control P.C. board?
Is there 2 V DC or less between
CN10A (+) and GND on
the indoor electronic control
P.C. board?
Yes
Turn OFF the power supply.
Remove the bridge between the
outdoor terminal block S2 and S3.
Reconnect the indoor/outdoor
connecting wire.
Turn ON the power supply.
Is there rated voltage between the
indoor terminal block S1 and S2?
<Confirmation of power voltage>
No
Replace the indoor
electronic control
P.C. board.*1
No
No
MXY-2G20VA MXY-2G20VA2
A
OBH779C
