10 Troubleshooting
Troubleshooting procedure
SMGB0091 rev.2 - 11/2015
208
Phenomenon
Cause
Check item
Action
(Turn OFF the main switch)
Power failure or no power supply
Measure the voltage
using the tester
Supply power
Melted fuse for
power source
or activation of
the RASC unit
breaker
Short circuit between wires
Check for breakage of
insulation
Remove cause of short circuit.
Replace fuse and/or indoor/
RASC unit PCB if faulty
Short circuited wire to ground
Measure the insulation
resistance
Remove cause of short circuit
to ground.
Replace fuse and/or indoor/
RASC PCB if faulty
Faulty compressor motor
Measure the resistance
between the wires and
the insulation resistance
Replace compressor and fuse
(RASC unit). Replace inverter
PCB and/or PCB1 if faulty
(RASC unit).
Melted fuse
for DC power
supply (RASC
unit) EF1, EF2
and EF3 on
PCB1 EF331 on
inverter PCB
Short circuit between wires
Check for breakage of
insulation
Remove cause of short circuit
and replace fuse.
Faulty solenoid coil for magnetic
switch (CMC) for compressor motor
Measure insulation
resistance
Remove cause of short circuit
and replace fuse
Incorrect power supply circuit of
RASC unit PCB1
Check RASC unit PCB1
output. *3)
Replace fuse
Melted fuse
RS1, RS2
Faulty CB
Measurement of
insulation resistance
Replace IPM or CB
Faulty IPM
Measurement of
resistance between lines
and insulation resistance
Replace IPM or PCB2 and
IPM
Incorrect power supply circuit of RASC unit PCB1
Measure RASC unit
PCB1 output. *3)
Replace RASC unit PCB1
Disconnected
wires insufficient
contacting
or incorrect
connection
Between RASC unit and indoor unit
Check the continuity
of the wires. Check
for looseness of the
connection screws.
Check the terminal
numbers
Replacing wires repairing and
tightening the screws and the
correct wiring
Power source wiring for the RASC
unit
Faulty PCB
(RASC unit,
indoor unit)
Disconnected wires to indoor/
RASC unit PCB
Check the connections
Correctly connect the wires
Faulty indoor/RASC unit PCB
Replace it if faulty
Incorrect wiring
Disconnected wire; insufficient
contacting
Check the continuity
and the looseness of
connection screws
Replacing wires, repairing and
tightening the screws
Incorrect wiring
Check terminal numbers
Correctly connect wires