Mitsubishi Electric MSZ-FD25VA Service Manual page 31

• Unit cannot operate neither by the remote controller nor by EMERGENCY OPERATION switch.
Indoor unit does not operate.
• POWER lamp flashes ON and OFF every 0.5-seconds.
Outdoor unit does not operate.
D How to check miswiring and serial signal error
A
· Turn OFF inverter-controlled lighting
equipment.
· Turn OFF the power supply and then
turn ON again.
· Press EMERGENCY OPERATION
switch.
· Reinstall
either the
unit or the
light each
Is serial signal
other away.
error indicated
· Attach a filter
No
6 minutes later? on remote
control
Yes
receiving
section of
the indoor
unit.
B
Turn OFF the power supply.
Is there rated voltage
in the power supply?
Yes
Turn ON the power supply.
Is there rated voltage between
outdoor terminal block S1 and
S2?
Yes
Press EMERGENCY OPERATION switch once.
Does AREA-L lamp light up?
<Confirmation of the power to the indoor unit>
Yes
Is serial signal error indicated 6 minutes later?
Yes
A
Turn OFF the power supply.
Check once more if the indoor/outdoor
connecting wire is not miswiring.
B
Short-circuit outdoor terminal block S2 and
S3.
W1
Turn ON the power supply.
Does the LED on the inverter P.C. board
or the outdoor electronic control P.C.board
repeat "3.6-second-OFF and 0.8-second-ON
quick blinking"? W3
Yes
Turn OFF the power supply.
Remove the short-circuit between
outdoor terminal block S2 and S3.
Turn ON the power supply.
Is there amplitude of 10 to 20 VDC
between outdoor terminal block S2
and S3? <Confirmation of serial
signal>
Yes
Is there rated voltage between
indoor terminal block S1 and S2?
<Confirmation of power voltage>
Yes
Replace the indoor electronic control P.C. board.
Be sure to release the failure-mode
recall function after checking.
Check the power
supply.
No
Check the wiring.
No
No
Is there any miswiring,
poor contact, or wire
disconnection of the
No
indoor/outdoor
connecting wire?
W1. Miswiring may damage indoor electronic control
P.C. board during the operation.
Be sure to confirm the wiring is correct before the
operation starts.
W3. Be sure to check this within 3 minutes after turning
ON. After 3 minutes, LED blinks 6 times. Even when
the inverter P.C.board or the outdoor electronic control
P.C.board is normal, LED blinks 6 times after
3 minutes.
(Except for outdoor unit of multi system type)
Replace the inverter P.C. board or
No
the outdoor electronic control P.C.board.
(Lighted or W2
not lighted)
W2 Be careful to the residual
voltage of smoothing capacitor.
Is there any error of the
indoor/outdoor connecting wire,
such as the damage of the wire,
intermediate connection, poor
No
contact to the terminal block?
No
Is there any error of the
indoor/outdoor connecting wire,
such as the damage of the wire,
No
intermediate connection, poor
contact to the terminal block?
No
31
Yes
Correct them.
No
Replace the
indoor/outdoor
Yes
connecting wire.
Replace the
indoor/outdoor
Yes
connecting wire.