31
Error Code
Abnormal point and detection method
Case
Judgment and action
U9
(4220)
Abnormality such as overvoltage
or voltage shortage and abnormal
synchronous signal to main circuit
Abnormal if any of followings are detected
during compressor operation;
•
Instantaneous decrease of DC bus volt-
age to 400V
•
Increase of DC bus voltage to 760V
• Decrease of input current of outdoor unit
to 0.5A only if operation frequency is
more than or equal to 40Hz or compres-
sor current is more than or equal to 5A.
1
Decrease of power supply voltage
2
Disconnection of compressor
wiring
3
Defective 52C drive circuit of
outdoor power circuit board
4
Disconnection or loose con-
nection of CN5 on the outdoor
power circuit board
5
Disconnection or loose con-
nection of CN2 on the outdoor
power circuit board
6
Defective outdoor controller cir-
cuit board
1
Check the facility of power supply.
2
Correct the wiring (U·V·W phase) to compressor.
Refer to 11-9 (Outdoor power circuit board).
3
Replace outdoor power circuit board.
4
Check CN5 wiring on the outdoor power
circuit board. Refer to 11-9.
5
Check CN2 wiring on the outdoor power
circuit board. Refer to 11-9.
6
Replace outdoor controller circuit board.
UF
(4100)
Compressor overcurrent interruption
(When compressor locked)
Abnormal if overcurrent of DC bus or
compressor is detected within 30 seconds
after compressor starts operating.
1
Stop valve is closed.
2
Decrease of power supply voltage
3
Looseness, disconnection or
converse of compressor wiring
connection
4
Defective compressor
5
Defective outdoor power board
6
Dip switch setting difference of
outdoor controller circuit board
1
Open stop valve.
2
Check facility of power supply.
3
Correct the wiring (U·V·W phase) to
compressor.
Refer to 11-9 (Outdoor power circuit board).
4
Check compressor.
Refer to 11-6.
5
Replace outdoor power circuit board.
6
Check the dip switch setting of outdoor con-
troller circuit board.
UH
(5300)
Compressor current sensor error or
input current error
Abnormal if compressor current sensor
detects –1.0A to 1.0A within 3 minutes
after compressor starts operating. (This
error is ignored in case of test run mode.)
1
Disconnection of compressor
wiring
2
Defective circuit of current
sensor on outdoor power
circuit board
1
Correct the wiring (U·V·W phase) to
compressor. Refer to 11-9 (Outdoor power
circuit board).
2
Replace outdoor power circuit board.
Ud
(1504)
Overheat protection
Abnormal if outdoor pipe thermistor (TH3)
detects 70
:
or more during compressor
operation.
1
Defective outdoor fan (fan
motor) or short cycle of outdoor
unit during cooling operation
2
Defective outdoor pipe ther-
mistor (TH3)
3
Defective outdoor controller board
1
Check outdoor unit air passage.
23
Turn the power off and on again to check
the error code. If U4 is displayed, follow the
U4 processing direction.
UL
(1300)
Low pressure
Abnormal if the following conditions are
detected for continuously 1-3 minutes after
compressor starts heating operation for 5
minutes.
1. Heating mode
Detection mode1
TH7-TH3
[
4
:
and
TH5-Indoor room temperature
[
2
:
Detection mode2
TH7-TH3
[
2
:
and
TH5-Indoor room temperature
[
4
:
and
TH2-Indoor room temperature
[
4
:
2.Cooling mode
TH6-TH7
[
2
:
and
TH3-TH7
[
2
:
and
Indoor room temperature - Indoor liquid
pipe temperature (TH2)
[
5
:
Thermistor
TH3: Outdoor liquid pipe temperature
TH5: Indoor cond./eva. temperature
TH6: Outdoor 2-phase pipe temperature
TH7: Outdoor temperature
1
Stop valve of outdoor unit is
closed during operation.
2
Leakage or shortage of refrigerant
3
Malfunction of linear expansion
valve
4
Clogging with foreign objects in
refrigerant circuit
w
Clogging occurs in the parts
which become below freez-
ing point when water enters in
refrigerant circuit.
1
Check stop valve.
2
Check intake superheat.
Check leakage of refrigerant.
Check additional refrigerant.
3
Check linear expansion valve.
Refer to 11-6.
4
After recovering refrigerant, remove water
from entire refrigerant circuit under vacuum
more than 1 hour.
OCH424E
