Mitsubishi Electric MSZ-EF18NAW-U1 Service Manual page 28

Indoor/outdoor units
Table of Contents

Advertisement

D How to check miswiring and serial signal error
Is the bus-bar voltage of the inverter P.C. board or the outdoor electronic control P.C. board
normal? (Refer to "TEST POINT DIAGRAM AND VOLTAGE" in the outdoor service manual.)
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"?
Turn OFF the power supply.
Remove the bridge between the outdoor terminal block S2 and S3.
Turn ON the power supply.
Is there rated voltage between the indoor terminal block S1 and S2?
<Confirmation of power voltage>
Is there amplitude of 10 to 20 V DC between the indoor terminal block
S2 and S3? <Confirmation of serial signal>
A
• Turn OFF inverter-controlled lighting
equipment.
• Turn OFF the power supply and then
turn ON again.
• Press the emergency operation switch.
• Reinstall
either the unit
or the light
away from
Is serial signal
each other.
error indicated 6
• Attach a filter
No
minutes later?
on remote
control
Yes
receiving
section of the
B
indoor unit.
OBH736C
Turn OFF the power supply.
Is there rated voltage in the power supply?
Yes
Turn ON the power supply.
Is there rated voltage between the outdoor terminal block S1 and S2?
Yes
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
Is serial signal error indicated 6 minutes later?
Yes
A
Turn OFF the power supply.
Check once more if the indoor/outdoor
B
connecting wire is not miswiring.
Bridge the outdoor terminal block S2 and
S3.
1
*
Turn ON the power supply.
Yes
3
*
Yes
Yes
Yes
Is there 2 V DC or less between CN102
and JPG (GND)(-) on the indoor electronic
control P.C. board?
Yes
No
Is there 2 V DC or less between
CN102
(+) and JPG (GND)(-) on
the indoor electronic control P.C.
board?
No
Replace the indoor power
P.C. board.
28
NOTE: Refer to the outdoor unit service manual.
Check the power supply.
No
No
No
Is there any miswiring,
poor contact, or wire
disconnection of the
No
indoor/outdoor connect-
ing wire?
No
1. Miswiring may damage indoor electronic control P.C.
*
board during the operation.
Be sure to confirm the wiring is correct before the opera-
tion starts.
3. Be sure to check this within 3 minutes after turning ON.
*
After 3 minutes, LED blinks 6 times. Even when the
inverter P.C. board is normal, LED blinks 6 times after
3 minutes. (Except for outdoor unit of multi system type)
Check of power supply.
(Refer to the outdoor
No
service manual.)
Replace the inverter P.C. board or the
outdoor electronic control P.C. board.
No
(Lit or
2. Be careful of the residual voltage of
*
not lit)
smoothing capacitor.
Check the wiring
If there are any errors of the indoor/outdoor connecting wire:
such as the damage of the wire, intermediate connection,
No
and/or poor contact to the terminal block, replace the indoor/
outdoor connecting wire.
No
(+)
Is there 2 V DC or less between
CN102
(+) and JPG (GND)(-) on
the indoor electronic control P.C.
board?
Yes
Replace the indoor electronic
control P.C. board.
Check the wiring.
Correct them.
Yes
2
*
Yes
No

Advertisement

Table of Contents
loading

Table of Contents