36
M How to check miswiring and serial signal error
Turn OFF the power supply.
Is there rated voltage AC in
the power supply?
Yes
No
Turn ON the power supply.
Check the power supply.
Is there rated voltage between
outdoor terminal block S1 and
S2?
No
Check the wiring.
Press the emergency operation switch once.
Does the left lamp of OPERATION INDICATOR
lamp light up? <Confirmation of the power to
the indoor unit>
Yes
No
Is serial signal error indicated 6 minutes later?
Yes
No
Is there any miswiring, poor
contact, or wire disconnec-
tion of the indoor/outdoor
connecting wire?
Is fuse (F65) broken?
Yes
Correct them.
No
A
Turn OFF the power supply.
Check once more if the indoor/outdoor
connecting wire is not miswiring.
Short-circuit outdoor terminal block S2
and S3. *1
B
*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.
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"?
Yes
No
(Lit or not
lit)
Replace the inverter P.C. board or the
outdoor electronic control P.C. board.
*2
*2. Be careful of the residual voltage
of smoothing capacitor.
Turn OFF the power supply.
Remove the short-circuit between out-
door 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? <Confirmation of serial signal>
Yes
No
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?
Yes
Replace the indoor/out-
door connecting wire.
Is there rated voltage between
indoor terminal block S1 and S2?
<Confirmation of power voltage>
No
No
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?
Yes
Replace the indoor/out-
door connecting wire.
No
Replace the indoor electronic control P.C. board.
Yes
Be sure to release the failure-mode recall function
after checking.
Yes
• Turn OFF inverter-controlled lighting
equipment.
• Turn OFF the power supply and then
turn ON again.
• Press the emergency operation switch.
A
Is serial signal
error indicated 6
minutes later?
B
Yes
• Reinstall
either the unit
or the light
away from
each other.
•
Attach a filter
on remote
control receiv-
ing section
of the indoor
unit.
No
OBH875A
