Mitsubishi Mr.SLIM MFZ-KA09NA Service Manual page 26

When the left lamp of OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second.
Outdoor unit does not operate.
D How to check miswiring and serial signal error
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
either the
unit or the
Is the serial
light away
No
signal error
from each
indicated 6
other.
minutes later? · Attach a filter
on receiving
section of
Yes
the indoor
unit.
B
OBH568A
Turn OFF the power supply.
Is there rated voltage of
230 VAC in the power
supply?
Yes
Turn ON the power supply.
Is there 230 VAC between
outdoor terminal block S1 and
S2?
Yes
Press EMERGENCY OPERATION switch once.
Does the left lamp of OPERATION INDICATOR
lamp light up? <Confirmation of the power
supply to the indoor unit>
Yes
Is the serial signal error indicated 6 minutes later?
Yes
A
Turn OFF the power supply.
Check once again if the indoor/outdoor
connecting wire is not wrongly connected.
B
Bridge the outdoor terminal block S2
and S3.
1
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 outdoor electronic control
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.
Yes
Remove the bridge between
outdoor terminal block S2 and S3.
Is there amplitude of 10 to 20 VDC
between outdoor terminal block S2
and S3? <Confirmation of serial
signal>
Yes
Is there 230 VAC between outdoor
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.
As for outdoor unit, refer to outdoor unit service manual.
26
No Check the power
supply.
No
Check the wiring.
No
Is there any miswiring,
poor contact, or wire
No
disconnection of the
indoor/outdoor
connecting wire?
No
1. Miswiring may damage indoor electronic control
P.C. board during operation.
Be sure to confirm the wiring is correct before the
operation starts.
Replace the outdoor
No
electronic control P.C.
(Lighting)
board. 2
2 Be careful of 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,
intermediate connection, poor
No
contact to the terminal block?
No
Yes
Make them sure.
Replace the
Yes
indoor/outdoor
connecting.
Replace the
Yes
indoor/outdoor
connecting.