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Check Code
Abnormal point and detection method
Overheat protection
Abnormal if outdoor liquid thermistor
(TH3) detects 70: or more or condensing
temperature of pressure sensor (63HS)
detects 70: or more during compressor
operation.
Ud
Compressor overcurrent interruption
(When compressor locked)
Abnormal if overcurrent of DC bus or
compressor is detected within 30 seconds
after compressor starts operating.
UF
Current sensor error or input current error
• Abnormal if current sensor detects −1.0
A to 1.0 A during compressor operation.
(This error is ignored during test run.)
UH
Compressor overcurrent interruption
Abnormal if overcurrent DC bus or
compressor is detected after compressor
starts operating for 30 seconds.
UP
OCH605A
Case
1 Defective outdoor fan (fan
motor) or short cycle of out-
door unit during cooling opera-
tion
2 Defective outdoor liquid
thermistor (TH3)
3 Defective outdoor controller
circuit board
4 Defective pressure sensor
1 Decrease of power supply
voltage
2 Looseness, disconnection or
converse of compressor wiring
connection
3 Defective compressor
4 Defective outdoor power board
5 Decreased water flow
6 Clogged filter of water pipe
7 Clogged plate heat exchanger
8 Locked water pump
9 Malfunction of water pump
1 Disconnection of compressor
wiring
2 Defective circuit of current
sensor on outdoor power
circuit board
3 Decrease of power supply
voltage
4 Leakage or shortage of
refrigerant
1 Decrease of power supply volt-
age
2 Looseness, disconnection or
converse of compressor wiring
connection
3 Defective fan of outdoor units
4 Short cycle of indoor/outdoor
units
5 Defective input circuit of out-
door controller circuit board
6 Defective compressor
7 Decreased water flow
8 Clogged filter of water pipe
9 Clogged plate heat exchanger
Locked water pump
0
Malfunction of water pump
1
19
Judgment and action
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.
4 Check pressure by microcomputer.
(Pressure sensor/ 63HS)
(SW2: Refer to "8-7. OUTDOOR UNIT
OPERATION MONITOR FUNCTION".)
1 Check facility of power supply.
V
W phase) to
•
•
2 Correct the wiring (U
compressor.
Refer to "8-6. TEST POINT DIAGRAM"
(Outdoor power circuit board).
3 Check compressor. Refer to
CHECK THE PARTS"
4 Replace outdoor power circuit board.
–
5
9 Check water circuit and repair the defect.
V
W phase) to compres-
•
•
1 Correct the wiring (U
sor. Refer to "8-6. TEST POINT DIAGRAM"
(Outdoor power circuit board).
2 Replace outdoor power circuit board.
3 Check the facility of power supply.
4 Check leakage of refrigerant.
1 Check facility of power supply.
V
W phase) to
•
•
2 Correct the wiring (U
compressor. Refer to "8-6. TEST POINT
DIAGRAM" (Outdoor power circuit board).
3 Check outdoor fan.
4 Solve short cycle.
5 Replace outdoor controller circuit board.
6 Check compressor.
Refer to "8-4. 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.
7–1 Check water circuit and repair the defect.
"8-4. HOW TO
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