How To Check Mis-Wiring And Serial Signal Error - Mitsubishi MSZ-FA25VA Service Manual

When POWER lamp flashes ON and OFF in every 0.5-second.
Outdoor unit does not operate.

How to check mis-wiring and serial signal error

D
Inverter P.C.board
(Parts side)
LED
Blinking
A
· Turn OFF inverter-controlled lighting
equipment.
· Turn OFF the power supply and then
turn ON again.
· Press EMERGENCY OPERATION
switch.
· Reinstall
Is serial signal
No
error indicated
· Attach a filter
6 minutes later?
Yes
B
Turn OFF the power supply.
Is there rated voltage of
230V AC in the power
supply?
Turn ON the power supply.
Is there 230V AC between
outdoor terminal block S1 and
S2?
Press EMERGENCY OPERATION switch.
Does POWER lamp light up?
<Confirmation of the power to the indoor unit>
Is the self-check of the indoor unit displayed 6
minutes after?
Serial signal error display
POWER lamp
blinks quickly.
Turn OFF the power supply.
Check once more if the indoor/outdoor
connecting wire is not mis-wiring.
B
Short-circuit outdoor terminal block S2 and
S3.
W1
Turn ON the power supply of the outdoor unit.
In 3 minutes after turning ON the
power supply of the outdoor unit, does
the LED on the inverter P.C. board
repeat quick blinking "3.6-second-OFF
and 0.8-second-ON"?
Be sure to check above in 3 minutes
after turning ON. After 3 minutes, LED
blinks 6 times. When the inverter P.C.
board is normal, LED also blinks 6
times after 3 minutes.
Remove the short-circuit between
outdoor terminal block S2 and S3.
Is there amplitude of 10 to 20V DC
between outdoor terminal block S2
and S3? <Confirmation of serial
signal>
either the
Is there 230V AC between outdoor
unit or the
terminal block S1 and S2?
light each
<Confirmation of power voltage>
other away.
on receiving
Replace the indoor electronic control P.C. board.
section of
the indoor
Be sure to release the failure-mode
unit.
recall function after checking.
As for outdoor unit MUZ type,refer to service manual OB372.
As for outdoor unit MXZ type,refer to service manual OB377.
No
Check the power
supply.
Yes
No
Check the wiring.
Yes
No
Yes
No
Yes
A
W1. Mis-wiring may damage indoor electronic control
P.C. board during the operation.
Be sure to confirm the wiring is correct before the
operation starts.
No
(Lighting)
Yes
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?
Yes
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?
Yes
24
Is there any mis-wiring,
poor contact, or wire
Yes
disconnection of the Make them sure.
indoor/outdoor
connecting wire?
No
Replace the inverter
P.C. board.
W2
W2 Be careful to the residual
voltage of smoothing capacitor.
Replace the
Yes
indoor/outdoor
connecting.
No
Replace the
Yes
indoor/outdoor
connecting.