50
OCH722A
Code
Error
Cause
Action
U4
(TH3:
5105)
(TH7:
5106)
(TH8:
5110)
(TH32:
5132)
(TH34:
5134)
Open/short of heat pump unit thermis-
tors
(TH3, TH32, TH34, TH7 and TH8)
Abnormal if open or short is detected during
compressor operation.
Open detection of TH3, TH32 and TH34 is
inoperative for 10 seconds to 10 minutes
after compressor starting.
Note:
Check which unit has abnormality in its
thermistor by switching the mode of SW2.
(PAC-SK52ST)
1.
Disconnection or contact failure of connectors
Controller circuit board: TH3, TH32, TH34, TH7
Power board: CN6
1.
Check connection of connector (TH3, TH32, TH34
TH7) on the controller circuit board.
Check connection of connector (CN6) on the
power board. Check breaking of the lead wire for
TH3, TH32, TH34, TH7, TH8.
2.
Defective thermistor
2.
Check resistance value of TH3, TH32,
TH34,TH7,TH8 or check temperature by micropro
-
cessor.
3. Defective controller circuit board
3. Replace controller circuit board.
Note:
Emergency operation is available in case of ab
-
normalities of TH3 and TH7.
U5
(4230)
Temperature of heat sink
Abnormal if TH8 detects temperature
indicated 95°C.
TH8: Thermistor <Heat sink>
1.
Rise of ambient temperature
1.
Check if there is something which causes tem
-
perature rise around unit.
(Upper limit of ambient temperature is 35°C.)
Turn off power, and on again to check if U5 is dis
-
played within 30 minutes.
If U4 is displayed instead of U5, follow the action
to be taken for U4.
2.
Defective thermistor
2.
Check resistance value of TH8 or temperature by
microprocessor.
3. Defective input circuit of power circuit board
3. Replace power circuit board.
4.
Failure of brine pump drive circuit
4.
Replace controller circuit board.
U6
(4250)
Power module
Check abnormality by driving power mod
-
ule in case overcurrent is detected.
(UF or UP error condition)
1.
Decrease of power supply voltage
1.
Check facility of power supply.
2.
Looseness, disconnection or converse of com
-
pressor wiring connection
2.
Correct the wiring (U•V•W phase) to compressor.
3. Defective compressor
3. Check compressor
4.
Defective controller circuit board
4.
Replace controller circuit board.
U7
(1520)
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 though linear
expansion valve has minimum open pulse
after compressor starts operating for 10
minutes.
1.
Disconnection or loose connection of discharge
temperature thermistor (TH4)
1., 2.
Check the installation conditions of discharge
temperature thermistor (TH4).
2.
Defective holder of discharge temperature thermis
-
tor
3. Disconnection or loose connection of linear
expansion valve’s coil
3. Check the coil of linear expansion valve.
4.
Disconnection or loose connection of linear
expansion valve’s connector
4.
Check the connection or contact of LEV-A on
controller circuit board.
5.
Defective linear expansion valve
5.
Check linear expansion valve.
U8
(4400)
Brine pump
Abnormal if rotational frequency of the
brine pump is not detected during DC brine
pump operation. Brine pump rotational
frequency is abnormal if 500 rpm or below
or 5000 rpm or more detected continuously
for 1 minute.
1.
Failure in the operation of the DC brine pump
1.
Check or replace the DC brine pump.
2.
Failure in the controller circuit board
2.
Check the voltage of the controller circuit board
during operation.
3. Replace the controller circuit board.
(When the failure is still indicated even after per
-
forming the action
1
above.)
U9
(4220)
Detailed
codes
To find out the details about U9 error, turn ON SW2-1, 2-2, 2-3, 2-4, 2-5 and 2-6 when U9 error occurs. (PAC-SK52ST)
To find out the detail history (latest) about U9 error, turn ON SW2-1, 2-2 and 2-6. (PAC-SK52ST)
Refer to "9-8. FUNCTION OF SWITCHES, CONNECTORS AND JUMPERS".
01
Overvoltage error
• Increase in DC bus voltage
to 760V
1.
Abnormal increase in power source voltage
1.
Check the field facility for the power supply.
2.
Disconnection of compressor wiring
2.
Correct the wiring (U.V.W phase) to compressor. Refer
to "9-8. FUNCTION OF SWITCHES, CONNECTORS
AND JUMPERS". (Power circuit board).
3. Defective power circuit board
3. Replace power circuit board.
4.
Compressor has a ground fault.
4.
Check compressor for electrical insulation.
Replace compressor.
02
Undervoltage error
• Instantaneous decrease in
DC bus voltage to 350V
1.
Decrease in power source voltage,
instantaneous stop
1.
Check the field facility for the power supply.
2.
Defective 52C drive circuit in power circuit board
2.
Replace power circuit board.
3. Defective converter circuit board
3. Replace converter circuit board.
4.
Disconnection or loose connection of rush
current protect resistor RS
4.
Check RS wiring.
5.
Defective rush current protect resistor RS
5.
Replace RS.
Summary of Contents for EHGT17D-YM9ED
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