Mitsubishi Electric MUZ-FH35VEHZ Service Manual page 46

M How to check miswiring and serial signal error
MUZ-FH25/35
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 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 POWER lamp
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 power supply OFF.
Replace the indoor power P.C.
board.
Turn the power supply ON.
Start the emergency operation.
Does the indoor POWER lamp
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.
OBH625G
Turn the power supply OFF.
Is there rated voltage in the power supply?
Yes
Check for incorrect indoor-outdoor connecting wiring.
Was the indoor unit ever connected to
the Multi (MXZ) series and operated
Yes
(turned on)?
A
B
Turn the power supply ON.
Yes
Does the outdoor LED light up?
No
Confirm that the thermostat is OFF
and wiring is not loose.
Replace the outdoor inverter P.C. board. *1
No
Replace the outdoor inverter P.C. board. *1
No
*1.
Electric charge may remain immediately
after the power supply is turned OFF.
Perform the procedure after 3 minutes.
Repair completed.
No
Replace the outdoor
No
inverter P.C. board. *1
Check the power supply.
No
No
No
No
No
Yes
Wait for 2 or more minutes after the power supply
is turned ON. Touch CN202
probes and start the emergency operation.
• 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 minutes later?
Yes
B
46
Check for miswiring, broken wires, and loose
wire connection between the power supply
and outdoor terminal block S1 and between
the power supply and outdoor terminal block
S2.
Turn the power supply OFF.
Turn the power supply ON.
and JPG with tester
During the emergency operation,
does DC (2V or more) occur for 2
seconds between CN202 and
JPG on the indoor electronic control
P.C. board?
Yes
Replace the
indoor power P.C.
board.
A
• Reinstall either the unit or the light
away from each other.
No • Attach a filter on remote control
receiving section of the indoor unit.
No
Replace the
indoor electronic
control P.C. board.