31
OCH721A
Check code Abnormal points and detection method
Cause
judgment and action
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
reversed of compressor wiring
connection
4
Defective compressor
5
Defective outdoor power board
6
DIP Switch setting for selecting
model is incorrect on the
outdoor power circuit board.
1
Open stop valve.
2
Check facility of power supply.
3
Correct the wiring (U·V·W phase) to
compressor. Refer to "10-9. TEST POINT
DIAGRAM".(Outdoor power circuit board).
4
Check compressor. Refer to "10-6. HOW TO
CHECK THE PARTS".
5
Replace outdoor power circuit board.
6
Check that the DIP Switch setting is cor-
rect on the outdoor controller circuit
board by referring to "Model Select" in "1)
Function of switches" in "10-10. FUNCTION
OF SWITCHES, CONNECTORS AND
JUMPERS".
UH
(5300)
Current sensor error
•
It is abnormal for 38A the input current or
10 seconds continuous 34A or more.
1
Defective circuit of current
sensor on outdoor power circuit
board
2
Decrease of power supply
voltage
1
Replace outdoor power circuit board.
2
Check the facility of power supply.
UL
(1300)
Low pressure
Abnormal if the following conditions are detected for
continuously 3 minutes after compressor starts heating
operating for 10 minutes.
1. Heating mode
Detection mode 1
TH7−TH3
[
4°C and
TH5−Indoor room temperature
[
2°C
Detection mode 2
TH7−TH3
[
2°C and
TH5−Indoor room temperature
[
4°C and
TH2−Indoor room temperature
[
4°C
Detection mode 3
TH7−TH3
[
4°C and
TH5−Indoor room temperature
[
2°C
and TH4−TH5
]
20°C
2. Cooling mode
TH6−TH7
[
2°C and
TH3−TH7
[
2°C and
Indoor room temperature - Indoor liquid
pipe temperature (TH2)
[
5°C
Note that it applies when the compressor
accumulated operating time is under 30
minutes, and 7 minutes has passed after
the compressor operation.
Thermistors:
TH3: Liquid pipe temperature
TH4: Discharge temperature
TH5: Indoor 2-phase pipe temperature
TH7: Ambient temperature
Thermistor TH3: Outdoor liquid pipe temperature
TH4: Discharge 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
Note:
If water enters in refrigerant
circuit, clogging may occur where
the part becomes below freezing
point.
1
Check stop valve.
2
Check intake superheat.
Check leakage of refrigerant.
Check additional refrigerant.
3
Check linear expansion valve.
Refer to "10-6. HOW TO CHECK THE
PARTS".
4
After recovering refrigerant, remove water
from entire refrigerant circuit under vacuum
more than 1 hour.
UP
(4210)
Compressor overcurrent interruption
Abnormal if overcurrent DC bus or com-
pressor is detected after compressor starts
operating for 30 seconds.
1
Stop valve of outdoor unit is
closed.
2
Decrease of power supply
voltage
3
Looseness, disconnection or
reversed of compressor wiring
connection
4
Defective fan of indoor/outdoor
units
5
Short cycle of indoor/outdoor
units
6
Defective input circuit of
outdoor power circuit board
7
Defective compressor
1
Open stop valve.
2
Check facility of power supply.
3
Correct the wiring (U·V·W phase) to
compressor. Refer to "10-9. TEST POINT
DIAGRAM" (Outdoor power circuit board).
4
Check indoor/outdoor fan.
5
Solve short cycle.
6
Replace Outdoor power circuit board.
7
Check compressor.
Refer to "10-6. HOW TO CHECK THE PARTS".
Note: Before the replacement of the outdoor controller
circuit board, disconnect the wiring to compressor
from the outdoor power circuit board and check the
output voltage among phases, U, V, W, during test
run. No defect on board if voltage among phases
(U-V, V-W and W-U) is same. Make sure to perform
the voltage check with same performing frequency.
