Remarks
circuit
unit
Indoor
unit
Outdoor
unit
LCD
Body
LED
Symptom that
can occur other
than title
Check method
(Error state check method)
Cause
measurement
Indoor
unit
Normal
display
Normal
display
Normal
display
Installed piping is not suitable.
Liquid piping diameter is
incorrect.
Check the capacity of indoor unit
and the pipe diameter.
When the diameter is large,
a refrigerant rushing sound is
generated and when
the diameter is small,
capacity will be insufficient.
High pressure
rises or falls
abnormally.
Refrigerant additional charge
is unsuitable.
Check the model and model code
of indoor units, liquid piping dia-
meter, pipe length and calculation
for additional charge.(Refer
to section 6-1).
When gas is insufficient,
the capacity drops and when
gas is excessive, the high
pressure rises abnormally.
Error display
(Outdoor
unit error)
Error display
(Communi-
cation error)
Error display
(Outdoor
unit error)
Indoor~outdoor unit
communication line faulty.
When one of communication
terminal board (Transmission)
terminals 1-2 of the indoor units
is shorted, the resistance
between1 and 2 of communi-
cation terminal board (Transmi-
ssion) of all the indoor units
become zero.
Normal
display
Normal
display
or
error display
(Compressor
error)
Normal
display
Refrigerant is seriously insuffici-
ent.
When the number of operating
indoor units was changed,
the discharge temperature of the
indoor units does not become
low or high.
When the gas insufficiency be-
come seriously, the high
pressure drops and
the discharge temperature
increases abnormally.
Error display
(Thermistor
error)
Error display
(Indoor unit
error)
Error display
(Thermistor
error)
The fan of the
indoor unit does
not rotate.
Indoor thermistor is faulty.
Measure the thermistor
resistance and compare it to
the ambient temperature.
Refer to section 7-2-1 to find the
correlation between the tempera-
ture and thermistor resistance.
05-40
Become normal after the power
is reset.
Indoor
unit
Indoor
unit
When short or open circuit of
thermistor occurred.
Abnormal sound
is heard from
indoor unit.
Outdoor heat exchanger
switching 4-way valves (4WV2,
4WV3, 4WV4) or solenoid valves
(SV7, SV8) are faulty.
When a 4-way valves or solenoid
valves are faulty, the high pres-
sure will rise during the cooling
operation and the low pressure
will fall during the heating
operation.
Coil resistance : 1200~1500 .
Normal
display
Error display
(High
pressure
error)
Normal
display
Miswring between RB unit and
indoor unit.
When a relevant indoor unit
performs the heating operation,
the high pressure becomes high
and warm air is not discharged
from the indoor unit.
Wring between RB unit and in-
door unit must correspond to the
piping connection.
(Trouble occurs especially easily
with the UTF-Y90A4A.)
Check the heat exchanger opera-
tion capacity at the LED on the
outdoor control PCB (Refer to
section 5-2).
Check the energized state
(AC220-240V) of the heat ex-
changer 4-way valve and solen-
oid valves.
Check the temperature of the
pipes connecting these valves.
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