Obh629 - Mitsubishi Electric MUZ-SF25VE-E1 Service Manual

M How to check miswiring and serial signal error
Check for incorrect indoor-outdoor connecting wiring.
Yes
The connection information to the Multi series is stored
in the indoor unit. Refer to "Deleting the memorized
abnormal condition" described in 11-2.1 to clear the error
history. When the error history is being cleared, the con-
nection information also will be initialized. The indoor unit
will be compatible with a low-standby-power model after
initialization.
OK
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?
Yes
Does the indoor OPERATION
INDICATOR lamp (left) blink
continuously 6 minutes after the
emergency operation starts?
Yes
Does the outdoor LED blink 6
times?
Yes
Does DC (6V or more) occur
between indoor terminal block S2
and S3?
Yes
Turn the main power supply OFF.
Replace the indoor power P.C.
board.
Turn the main power supply ON.
Start the emergency operation.
Does the indoor OPERATION
INDICATOR lamp (left) blink
continuously 6 minutes after the
emergency operation starts?
Yes
Does DC (20V or more) occur
between indoor terminal block S2
and S3 ?
Yes
Replace the indoor electronic
control P.C. board.

OBH629

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)?
A
B
Turn the main power supply ON.
Yes
No
Does the outdoor LED light up?
Yes
Confi rm that the thermostat is OFF
and wiring is not loose.
No
Replace the outdoor inverter P.C. board. 1
No
Replace the outdoor inverter P.C. board. 1
1.
Electric charge may remain immediately
after the main power supply is turned OFF.
Perform the procedure after 3 minutes.
No
Repair completed.
No
Replace the outdoor
inverter P.C. board. 1
Check the power supply.
No
No
Check for miswiring, broken wires, and loose
wire connection between the main power
No
supply and outdoor terminal block S1 and
between the main power supply and outdoor
terminal block S2.
No
Turn the main power supply
OFF.
No
Turn the main power supply
ON.
Wait for 2 or more minutes after the main power sup-
ply is turned ON. Touch CN202
probes and start the emergency operation.
During the emergency operation,
does DC (2V or more) occur for 2
seconds between CN202
JPG on the indoor electronic control
P.C. board?
• Turn OFF inverter-controlled lighting equipment.
• Turn OFF the power supply and then turn ON again.
• Press EMERGENCY OPERATION switch.
Is serial signal
error indicated 6
No
minutes later?
Yes
B
41
and JPG with tester
No
and
Yes
Replace the Replace the
indoor power P.C. indoor electronic
board. control P.C. board.
A
• Reinstall either the unit or the light
away from each other.
• Attach a fi lter on remote control
receiving section of the indoor unit.