40
OCH737
Check Code Abnormal points and detection method
Cause
Judgment and action
Ud
(UD)*
(1504)
Over heat 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 thermistor
(TH3)
3
Defective outdoor controller board
1
Check outdoor unit air passage.
23
Turn the power off and on again to
check the check code. If U4 is displayed,
follow the U4 processing direction.
*The check code in the parenthesis indicates
PAR-4xMAA model ("x" represents 0 or
later).
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 con-
verse of compressor wiring con-
nection
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 "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 the DIP switch setting of outdoor
controller circuit board. Refer to "Model
Select" in "(1) Function of switches" in
"10-10. FUNCTION OF SWITCHES,
CONNECTORS AND JUMPERS".
UH
(5300)
Current sensor error or input current error
•
Abnormal if current sensor detects −1.0A
to 1.0A during compressor operation. (This
error is ignored in the case of test run
mode.)
1
Disconnection of compressor
wiring
2
Defective circuit of current sensor
on outdoor power circuit board
3
Decrease of power supply voltage
1
Correct the wiring (U
•
V
•
W phase) to
compressor. Refer to "10-9. TEST POINT
DIAGRAM" (Outdoor power circuit board).
2
Replace outdoor power circuit board.
3
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.
TH7−TH3
[
4°C and
TH5−Indoor room temperature
[
2°C
Thermistor TH3: Outdoor liquid pipe temperature
TH5: Indoor cond./eva. temperature
TH7: Ambient 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 vacu-
um more than 1 hour.
UP
(4210)
Compressor overcurrent interruption
Abnormal if overcurrent DC bus or compres-
sor is detected after compressor starts oper-
ating for 30 seconds.
1
Stop valve of outdoor unit is
closed.
2
Decrease of power supply voltage
3
Looseness, disconnection or con-
verse of compressor wiring con-
nection
4
Defective fan of indoor/outdoor
units
5
Short cycle of indoor/outdoor units
6
Defective input circuit of outdoor
controller board
7
Defective compressor
8
Defective outdoor power circuit board
9
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 com-
pressor. Refer to "10-9. TEST POINT
DIAGRAM". (Outdoor power circuit board).
4
Check indoor/outdoor fan.
5
Solve short cycle.
6
Replace outdoor controller circuit board.
7
Check compressor. Refer to "10-6. HOW
TO CHECK THE PARTS".
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.
8
Replace outdoor power circuit board
9
Check the DIP switch setting of outdoor
controller circuit board
