Troubleshooting By Inferior Phenomena - Mitsubishi Electric M Series Service Manual

12-4. Troubleshooting by inferior phenomena

Phenomena
(1)LED2 on indoor controller board
is off.
(2)LED2 on indoor controller board
is blinking.
Cause
• When LED1 on indoor controller board is also off.
1 Power supply of rated voltage is not supplied to out-
door unit.
2 Defective outdoor controller circuit board
3 Power supply of 208~230V is not supplied to indoor
unit.
4 Defective indoor controller board
• When LED1 on indoor controller board is also blinking.
Connection failure of indoor/outdoor unit connecting
wire
• When LED1 is lit.
1 Mis-wiring of remote controller wires
Under twin triple indoor unit system, 2 or more indoor
units are wired together.
2 Refrigerant address for outdoor unit is wrong or not
set.
Under grouping control system, there are some units
whose refrigerant address is 0.
3 Short-cut of remote controller wires
4 Defective remote controller
33
Note: Refer to the manual of outdoor unit for the detail of remote
controller.
1 Check the voltage of outdoor power
supply terminal block (L, N) or (L
• When AC 208~230V is not detected.
Check the power wiring to outdoor unit
and the breaker.
• When AC 208~230V is detected.
—Check 2 (below).
2 Check the voltage between outdoor
terminal block S1 and S2.
• When AC 208~230V is not detected.
Check the fuse on outdoor controller
circuit board.
Check the wiring connection.
• When AC 208~230V is detected.
—Check 3 (below).
3 Check the voltage between indoor terminal
block S1 and S2.
• When AC 208~230V is not detected.
Check indoor/outdoor unit connecting
wire for mis-wiring.
• When AC 208~230V is detected.
—Check 4 (below).
4 Check the fuse on indoor controller board.
Check the wiring connection.
If no problem are found, indoor controller
board is defective.
Check indoor/outdoor unit connecting wire
for connection failure.
1 Check the connection of remote con-
troller wires in case of twin triple indoor
unit system. When 2 or more indoor units
are wired in one refrigerant system,
connect remote controller wires to one of
those units.
2 Check the setting of refrigerant address in
case of grouping control system.
If there are some units whose refrigerant
addresses are 0 in one group, set one of
the units to 0 using SW1 (3-6) on outdoor
controller circuit board.
34 Remove remote controller wires and
check LED2 on indoor controller board.
• When LED2 is blinking, check the
short-cut of remote controller wires.
• When LED2 is lit, connect remote
controller wires again and:
if LED2 is blinking, remote controller
is defective; if LED2 is lit, connection
failure of remote controller terminal
block etc. has returned to normal.
Countermeasure
, N).
3
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