Mitsubishi Electric MSZ-AP71VG-E3 Service Manual page 43

D How to check miswiring and serial signal error
MUZ Type
Check for incorrect indoor-outdoor connecting wiring.
Is there rated voltage between outdoor terminal block S1 and S2?
Wait for 2 or more minutes after the main power supply is turned on.
Touch S2 and S3 with tester probes and start the emergency operation.
When the emergency operation starts, does the rated voltage occur for 2
seconds between indoor terminal block S2 and S3?
Does the indoor upper lamp of OPERATION
INDICATOR lamp blink continuously 6 min-
utes after the emergency operation starts?
Does the outdoor LED blink 6
times?
Does DC (6 V or more) occur
between indoor terminal block S2
and S3?
MUZ-AP25/35/
MUZ-AP42/50/60
Turn the power supply OFF.
Replace the indoor electronic
control P.C. board.
Turn the power supply ON.
Start the emergency operation.
Does the indoor upper lamp of
OPERATION INDICATOR lamp
blink continuously 6 minutes after
the emergency operation starts?
Does DC (20 V or more) occur
between indoor terminal block S2
and S3?
Replace the indoor electronic
control P.C. board.
OBH788E
Turn the main power supply
OFF.
Is there rated voltage in the power supply?
Yes
Was the indoor unit ever connected to
the Multi (MXZ) series and operated
(turned on)?
No
A
B Turn the main power supply ON.
Yes
Yes
No
Yes
No
Yes
No
Yes
MUZ-AP71
No
Yes
No
Yes
Check the power supply.
No
The connection information to the Multi series is stored in the
indoor unit. Refer to "Deleting the memorized abnormal condi-
tion" described in 10-2.1 to clear the error history. When the error
history is being cleared, the connection information also will be
Yes
initialized. The indoor unit will be compatible with a low-standby-
power model after initialization.
No
No
Does the outdoor LED light up?
Yes
Confirm that the thermostat is OFF
and wiring is not loose.
Replace the outdoor inverter P.C. board.
Replace the outdoor inverter P.C. board.
Electric charge may remain immediately
*1
after the power supply is turned OFF.
Perform the procedure after 3 minutes.
Repair completed.
Replace the outdoor inverter P.C. board.
43
OK
Check for miswiring, broken wires, and loose
wire connection between the main power
supply and outdoor terminal block S1 and
between the main power supply and outdoor
terminal block S2.
Replace the indoor
electronic control
No
P.C. board.
*1
*1
A
• Turn OFF inverter-controlled lighting
equipment.
• Turn OFF the power supply and then
turn ON again.
• Press the emergency operation switch.
Is serial signal
*1 error indicated 6
No
minutes later?
Yes
B
• Reinstall
either the unit
or the light
away from
each other.
• Attach a filter
on remote
control receiv-
ing section
of the indoor
unit.