Mitsubishi Electric MUFZ-KW25VG-E1 Service Manual page 47

M How to check miswiring and serial signal error
Does the left lamp of OPERATION INDICATOR lamp light up?
<Confirmation of the power supply to the indoor unit>
Turn OFF the power supply. Check once again if the indoor/out-
B door connecting wire is not wrongly connected.
Short-circuit the outdoor terminal block S2 and S3. *1
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 left lamp of OPERATION
INDICATOR lamp on indoor unit
blink continuously 6 minutes after
the emergency operation starts?
Yes
Does the outdoor LED blink 6
times?
Yes
Does DC (6 V 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 left lamp of OPERATION
INDICATOR lamp on indoor unit
blink continuously 6 minutes after
the emergency operation starts?
Yes
Does DC (20 V or more) occur
between indoor terminal block S2
and S3?
Yes
Replace the indoor electronic
control P.C. board.
OBH895
Turn the power supply OFF.
Is there rated voltage of 230 V AC in the
power supply?
Yes
Turn the power supply ON.
Is there 230 V AC between outdoor terminal
block S1 and S2?
Yes
Press the emergency operation switch once.
Yes
Is the serial signal error indicated 6 minutes
later?
Yes
A
Turn the power supply ON.
Does the outdoor LED light up?
No
Yes
Confirm that the thermostat is OFF
and wiring is not loose.
Replace the outdoor inverter P.C. board.*2
No
Replace the outdoor inverter P.C. board.*2
No
*2 Electric charge may remain immediately
after the power supply is turned OFF.
Perform the procedure after 3 minutes.
Repair completed.
No
Replace the outdoor inverter P.C. board.
No
Check the power supply.
No
Check for miswiring, broken wires, and loose
wire connection between the power supply and
outdoor terminal block S1 and between the
No
power supply and outdoor terminal block S2.
No
Is there any miswiring, poor con-
tact, or wire disconnection of the
No
indoor/outdoor connecting wire?
*1 Miswiring may damage indoor electron-
ic control P.C. board during operation.
Be sure to confirm the wiring is correct
before theoperation starts.
No
Turn the power supply OFF.
No
Turn the power supply ON.
Wait for 2 or more minutes after the
power supply is turned ON. Touch
CN202 and GND with tester probes
and start the emergency operation.
During the emergency opera-
tion, does DC (2V or less) occur
for 2 seconds between CN202
and GND on the indoor power
P.C. board?
Replace the
indoor power P.C.
board.
47
Correct them.
Yes
No
No
Yes
Replace the indoor
electronic control
P.C. board.
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
Yes control receiv-
ing section
of the indoor
B
unit.