Service manual

Error Code
Abnormal points and detection method
Case
Judgment and action
20
UP
Compressor overcurrent interruption
Abnormal if overcurrent DC bus or
compressor 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
converse of compressor wiring
connection
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
compressor. Refer to 10-9 (Outdoor power
circuit board).
4 Check indoor/outdoor fan.
5 Solve short cycle.
6 Replace outdoor controller circuit board.
W 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 Check compressor. Refer to 10-6.
8 Replace outdoor power circuit board.
9 Check the dip switch setting of outdoor
controller circuit board.
UF
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 10-9 (Outdoor power circuit board).
4 Check compressor.
Refer to 10-6.
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.
Ud
Over heat protection
Abnormal if liquid thermistor (TH3) detects
70: or more during compressor opera-
tion.
1 Defective outdoor fan (fan
motor) or short cycle of out-
door unit during cooling opera-
tion
2 Defective liquid thermistor
(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.
UE
Abnormal pressure of pressure sensor
(63HS)
Abnormal if pressure sensor (63HS)
detects 0.1 MPa or less.
Detection is inoperative for 3 minutes after
compressor starting and 3 minutes after
and during defrosting.
1 Disconnection or contact
failure of connector (63HS) on
the outdoor controller circuit
board
2 Defective pressure sensor
3 Defective outdoor controller
circuit board
1 Check connection of connector (63HS) on
the outdoor controller circuit board.
Check breaking of the lead wire for
thermistor (63HS).
2 Check pressure by microprocessor.
(Pressure sensor/ 63HS)
(SW2: Refer to 10-10.)
3 Replace outdoor controller board.
UH
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 case of test run mode.)
• Abnormal if 40A of input current is
detected or 37A or more of input current
is detected for 10 seconds continuously.
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 (Outdoor power
circuit board).
2 Replace outdoor power circuit board.
3 Check the facility of power supply.
OCH525