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7
Water to Water Heat Pump (WTW)
Code
Error
Too low superheat due to low
discharge temperature
Abnormal if discharge superheat is
continuously detected less than or
equal to −15°C for 3 minutes even
U7
though linear expansion valve
(1502)
has minimum open pulse after
compressor starts operating for 10
minutes.
Brine pump
Abnormal if rotational frequency
of the brine pump is not detected
during DC brine pump operation.
U8
Brine pump rotational frequency
(4400)
is abnormal if 500 rpm or below or
5000 rpm or more detected con-
tinuously for 1 minute.
U9
Abnormal voltage error
(4220)
See service handbook.
Abnormal pressure of 63HS
Abnormal if 63HS detects 0.1 MPa
or less.
Detection is inoperative for 3 min-
UE
utes after compressor starting and
(1302)
3 minutes after and during defrost-
ing.
63HS: High pressure sensor
Low pressure
Abnormal if TH33-TH4 exceeds
UL
20°C and TH33 exceeds 80°C dur-
(1300)
ing compressor operation.
Compressor overcurrent inter-
ruption
(When compressor locked)
UF
Abnormal if overcurrent of DC bus
(4100)
or compressor is detected within
30 seconds after compressor
starts operating.
Current sensor error or input
current error
• Abnormal if current sensor de-
tects –1.0A to 1.0A during com-
UH
pressor operation. (This error is
(5300)
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.
Low brine flow rate (flow switch
operated)
Abnormal if flow switch is operated
(under 5.5L/min) during compres-
sor operation.
UA
(2511)
Compressor overcurrent inter-
ruption
UP
Abnormal if overcurrent DC bus
(4210)
or compressor is detected after
compressor starts operating for 30
seconds.
B-262
Cause
Disconnection or loose connection
of discharge temperature thermistor
(TH4)
Defective holder of discharge tempera-
ture thermistor
Disconnection or loose connection of
linear expansion valve's coil
Disconnection or loose connection of
linear expansion valve's connector
Defective linear expansion valve
Failure in the operation of the DC brine
pump
Failure in the C.B.
See service handbook.
Disconnection or contact failure of
connector (63HS) on the C.B.
Defective pressure sensor
Defective C.B.
Defective linear expansion valve.
Defective C.B.
Decrease of power supply voltage
Looseness, disconnection or converse
of compressor wiring connection
Defective compressor
Defective power board
Disconnection of compressor wiring
Defective circuit of current sensor on
power circuit board
Decrease of power supply voltage
Leakage or shortage of refrigerant
Valve or PICV of ambient loop circuit is
closed during operation.
Disconnection or loose connection of
connector (63L) on C.B.
Disconnection or loose connection of
63L
Defective C.B.
Misconnection of Water/Brine pipe.
See service handbook.
Action
Check the installation conditions of
discharge temperature thermistor
(TH4).
Check the coil of linear expansion valve.
Check the connection or contact of
LEV-A on C.B.
Check linear expansion valve.
Check or replace the DC brine pump.
Check the voltage of the C.B. during
operation.
Replace the C.B.
(When the failure is still indicated
even after performing the action
above.)
See service handbook.
Check connection of connector
(63HS) on the C.B.
Check breaking of the lead wire for
63HS.
Check pressure by microprocessor.
(Pressure sensor/ 63HS)
Replace C.B.
Check linear expansion valve.
Replace C.B.
Check facility of power supply.
Correct the wiring (U•V•W phase) to
compressor.
Check compressor.
Replace power circuit board.
Correct the wiring (U•V•W phase) to
compressor.
Replace power circuit board.
Check the facility of power supply.
Check leakage of refrigerant.
Check valve or PICV.
Active SW6-4 on FTC, if TBI.4 7-8 is
connected.
-
Turn the power off and on again
to check if F3 is displayed on
restarting.
If F3 is displayed, follow the F3
processingdirection.
Check Water/Brine pipe connection.
See service handbook.
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