Mitsubishi Electric MUZ-DW25VF-E1 Service Manual page 44

M How to check miswiring and serial signal error
Is there rated voltage in the power supply?
Check for incorrect indoor-outdoor connecting wiring.
• Turn OFF inverter-controlled lighting equipment.
• Turn OFF the power supply and then turn ON again.
• Press the emergency operation switch.
Is serial signal error indicated 6 minutes later?
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 multimeter 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 (upper) 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 OPERATION
INDICATOR lamp (upper) 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.
OBH906A
Turn the power supply OFF.
Yes
Yes
Turn the power supply ON.
Yes
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. *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 inverter P.C. board. *1
No
Check the power supply.
No
• Reinstall either the unit or the light away from each other.
• Attach a filter on remote control receiving section of the
No
indoor unit.
Check for miswiring, broken wires, and loose
wire connection between the power supply
and outdoor terminal block S1, and between
No
the power supply and outdoor terminal block
S2.
No
No
Turn the power supply OFF.
Turn the power supply ON.
Wait for 2 or more minutes after the power
supply is turned ON. Touch CN10A
GND with multimeter probes and start the
emergency operation.
During the emergency opera-
tion, does DC (2V or less) occur
for 2 seconds between CN10A
and GND on the indoor elec-
tronic control P.C. board?
Replace the
indoor power P.C.
board.
44
and
No
Yes
Replace the
indoor electronic
control P.C. board.