Table of Contents
• When unit cannot operate neither by the remote controller nor by EMERGENCY OPERATION switch.
Indoor unit does not operate.
• When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second.
Outdoor unit does not operate.
How to check miswiring and serial signal error (when outdoor unit does not work)
LED indication
for communication status
Communication status is indicated
by the LED.
Unit status
Blinking: normal communication
Lighting: abnormal communication or
not connected
Pattern 1 and 2 is repeatedly displayed
alternately. Each pattern is displayed for
10 seconds.
NOTE: "Lighting" in the table below does not
indicate abnormal communication.
Outdoor control P.C. board
LED1 LED2 LED3
Blinking
Pattern
LED 1
LED 2
Unit A
Unit B
1
status
status
Unit C
Unit D
2
status
status
Unit E
3
status
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 away
Is serial signal
from each
No
error indicated
other.
6 minutes later?
· Attach a filter
on remote
control
receiving
section of
Yes
the indoor
unit.
B
OBH723D
Turn OFF the power supply.
Is there rated voltage in
the power supply?
Turn ON the power supply.
Is there rated voltage between
outdoor terminal block S1 and
S2?
Press EMERGENCY OPERATION switch once.
Does the left lamp of OPERATION
INDICATOR lamp light up?
LED 3
Lighted
Is serial signal error indicated 6 minutes later?
Not lighted
Blinking
Turn OFF the power supply.
Check once more if the indoor/outdoor
connecting wire is not miswiring.
B
Bridge the outdoor terminal block S2 and
S3.
1
Turn ON the power supply.
Does the LED on the outdoor control P.C.
board repeat "3.6-second-OFF
and 0.8-second-ON quick blinking"?
Turn OFF the power supply.
Remove the bridge between
outdoor terminal block S2 and S3.
Turn ON the power supply.
Is there amplitude of 10 to 20 V DC
between outdoor terminal block S2
and S3?
signal>
Is there rated voltage between
indoor terminal block S1 and S2?
Replace the indoor electronic control P.C. board.
Be sure to release the failure-mode
recall function after checking.
Refer to indoor unit service manual.
No
Check the power
supply.
Yes
No
Check the wiring.
Yes
No
Yes
Is there any miswiring,
poor contact, or wire
No
disconnection of the
indoor/outdoor
connecting wire?
Yes
A
1 Miswiring may damage indoor electronic control
P.C. board during the operation.
Be sure to confirm the wiring is correct before the
operation starts.
No
(Lighted
or
not lighted)
Yes
No
Yes
Is there any error of the
indoor/outdoor connecting wire,
such as the damage of the wire,
intermediate connection, poor
contact to the terminal block?
No
Yes
94
Yes
Correct them.
No
Replace the outdoor control P.C. board.
2
2 Be careful of the residual
voltage of smoothing capacitor.
Replace the
Yes
indoor/outdoor
connecting wire.
No
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