Toshiba MXZ-2DM40VA Service Manual page 36

• When the indoor unit does not operate, it cannot be operated either with the remote controller or with the
EMERGENCY OPERATION switch.
• When the outdoor unit does not operate, the OPERATION INDICATOR lamp on the indoor unit flashes ON and OFF
every 0.5-second.
How to check miswiring and serial signal error (when outdoor unit does not work)
LED indication for communication status
Communication status is indicated by the LED.
Unit status
Blinking: normal communication
Lighted: abnormal communication or not connected
Not lighted: The outdoor P.C. board is abnormal.
NOTE: "Lighted" and "Not lighted" in the table below
does not indicate abnormal.
MXZ-2DM40VA
Outdoor display P.C. board
LED1 LED2
LED 1 LED 2
Unit A Unit B
status status
MXZ-3DM50VA
Outdoor control P.C. board
LED3 LED2 LED1
Blinking
Pattern LED 3 LED 2
Unit B
Lighted
1
status
2
-
Not lighted
OBH739A
Turn ON the breaker.
Is there rated voltage
between outdoor
terminal block S1 and S2?
Y
Press the EMERGENCY
OPERATION switch
once.
Does the OPERATION
INDICATOR lamp light
up? <Confirmation of
the power to the indoor
unit>
Yes
Is serial signal error
indicated 6 minutes
later?
Y
Is there any miswiring,
poor contact, or wire
disconnection of the
LED 1
indoor/outdoor
Unit A
connecting wire?
status
No
Unit C
status
Turn OFF the breaker.
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. Short-circuit
between S2 and S3 of the
outdoor terminal block.
Turn ON the breaker.
Does the LED on the
outdoor display P.C.
board or the outdoor control
P.C. board repeat quick
BLINKING and OFF? *2
No
Replace the inverter P.C.
board or the outdoor control
P.C. board. *3 *4
Check the power supply
No
and correct the problem.
s e
Replace the indoor
electronic control
P.C. board. *1
Is there rated
voltage between
N o
outdoor terminal
block S1 and S2?
N o
s e
Check the indoor/outdoor
Y s e
connecting wire and
correct the problem.
*2 The LED indicates the status of serial communication.
Check the communication status.
Replace the indoor
Yes
electronic control
P.C. board. *1 *4
(Lighted or
not lighted)
*1 Turn OFF the breaker before replacing the indoor electronic control
P.C. board.
Refer to indoor unit service manual.
*3 Turn OFF the breaker before replacing the inverter P.C. board.
Be careful of residual voltage of smoothing capacitor.
*4 Remove the short-circuit between outdoor terminal block
S2 and S3. Connect the indoor/outdoor connecting wire.
36
*1 Turn OFF the breaker before
replacing the indoor electronic
control P.C. board.
Refer to indoor unit service manual.
Check the indoor/outdoor
N o
connecting wire and
correct the problem.
A
If the trouble sometimes occurs,
possible causes are as follows:
A
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).
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.
connecting wire
Pass the indoor/outdoor connecting
wire through a different route if the
existing wiring is arranged as below:
runs near the power supply cable of
other equipment.
is detoured and run long.