Mitsubishi Electric MXZ-2HA40VF-E1 Service Manual page 52

• When the indoor unit does not operate, it cannot be operated either with the remote controller or with the emergen-
cy operation switch.
• When the outdoor unit does not operate, the OPERATION INDICATOR lamp on the indoor unit blinks ON and OFF
every 0.5-second.
How to check miswiring and serial signal error (when outdoor unit does not work)
MXZ-2HA40VF/2HA50VF
LED indication for communication status
Communication status is indicated by the LED.
Unit status
Blinking: normal communication
Lit: abnormal communication or not connected
Not lit: The outdoor P.C. board is abnormal.
Outdoor display P.C. board
LED1 LED2
Blinking
LED 1 LED 2
Unit A Unit B
status status
OBH828B
Turn ON the power supply.
Is there rated voltage
between outdoor
No
terminal block S1 and S2 ?
Y s e
Press the emergency
operation switch
once.
Does the OPERATION
INDICATOR lamp light
up? <Confirmation of
N o
the power to the indoor
unit>
Yes
Is serial signal error
indicated 6 minutes
N o
later?
Y s e
Is there any miswiring,
poor contact, or wire
disconnection of the
indoor/outdoor
Y s e
connecting wire?
No
Turn OFF the power supply.
Remove the indoor/out-
door 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 power supply.
Does the LED on the
outdoor display P.C.
board or the outdoor control
Yes
P.C. board repeat quick
BLINKING and OFF? *2
No (Lit or *1 Turn OFF the power supply before replacing the indoor electronic
control P.C. board.
not lit)
Refer to indoor unit service manual.
*2 The LED indicates the status of serial communication.
Replace the inverter P.C.
Check the communication status.
board or the outdoor control
*3 Turn OFF the power supply before replacing the inverter P.C. board.
P.C. board. *3 *4
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.
52
Check the power supply
and correct the problem.
Replace the indoor
electronic control
P.C. board. *1
Is there rated
Check the indoor/outdoor
voltage between
connecting wire and
outdoor terminal
N o
correct the problem.
block S1 and S2?
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).
Check the indoor/outdoor
• Effects of the inverter lighting
connecting wire and
on the indoor unit
correct the problem.
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.
Replace the indoor
electronic control
P.C. board. *1 *4