How To Check Mis-Wiring And Serial Signal Error - Mitsubishi Electric MFZ-KA25VA Service Manual

When the left lamp of OPERATION INDICATOR 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 it ON again.
· Press EMERGENCY OPERATION
switch.
· Reinstall
Is the serial
No
signal error
indicated 6
minutes later?
· Attach a filter
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 once.
Does the left lamp of OPERATION INDICATOR
lamp light up? <Confirmation of the power
supply to the indoor unit>
Is the serial signal error indicated 6 minutes later?
Turn OFF the power supply.
Check once again if the indoor/outdoor
connecting wire is not wrongly connected.
B
Short-circuit the 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 away
<Confirmation of power voltage>
from the
other.
on receiving
Replace the indoor electronic control P.C. board.
section of
the indoor
Be sure to release the failure-mode recall function after checking.
unit.
As for outdoor unit, refer to outdoor unit service manual.
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 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
31
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.
No