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Checkcode Abnormal points and detection method
Open/short of outdoor unit thermistors
(TH3, TH6, TH7, and TH8)
Abnormal if open or short is detected during
compressor operation.
Open detection of thermistors TH3 and TH6
is inoperative for 10 seconds to 10 minutes
after compressor starting and 10 minutes
after and during defrosting.
Note: Check which unit has abnormality
in its thermistor by switching the
U4
mode of SW2. (PAC-SK52ST) (Refer
(TH3: 5105)
to "10-10. FUNCTION OF SWITCHES,
(TH6: 5107)
CONNECTORS AND JUMPERS".)
(TH7: 5106)
(TH8: 5110)
Symbol
TH3
TH6
TH7
TH8
Temperature of heat sink
Abnormal if heat sink thermistor (TH8)
detects temperature indicated below.
ZM35/50VKA ······························ 84°C
ZM60/71VHA ······························ 77°C
U5
(4230)
Power module
Check abnormality by driving power module
in case overcurrent is detected.
(UF or UP error condition)
U6
(4250)
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
U7
expansion valve has minimum open pulse
(1520)
after compressor starts operating for 10
minutes.
Outdoor fan motor
Abnormal if rotational frequency of the fan
motor is not detected during DC fan motor
operation.
Fan motor rotational frequency is abnormal
U8
if;
(4400)
• 100 rpm or below detected continuously
for 15 seconds at 20°C or more outside
air temperature.
• 50 rpm or below or 1500 rpm or more
detected continuously for 1 minute.
OCH653C
Cause
1 Disconnection or contact fail-
ure of connectors
(
Outdoor controller circuit
board: TH3, TH6/TH7
Outdoor power circuit board:
CN6
2 Defective thermistor
3 Defective outdoor controller
circuit board
Thermistors
Name
Thermistor <Liquid>
Thermistor <2-phase pipe>
Thermistor <Ambient>
Thermistor <Heat sink>
1 The outdoor fan motor is locked.
2 Failure of outdoor fan motor
3 Airflow path is clogged.
4 Rise of ambient temperature
5 Defective thermistor
6 Defective input circuit of
outdoor power circuit board
7 Failure of outdoor fan drive
circuit
1 Outdoor stop valve is closed.
2 Decrease of power supply
voltage
3 Looseness, disconnection or
reverse of compressor wiring
connection
4 Defective compressor
5 Defective outdoor power
circuit boar
1 Disconnection or loose
connection of discharge
temperature thermistor (TH4)
2 Defective holder of discharge
temperature thermistor
3 Disconnection or loose
connection of linear expansion
valve's coil
4 Disconnection or loose
connection of linear expansion
valve's connector
5 Defective linear expansion valve
1 Failure in the operation of the
DC fan motor
2 Failure in the outdoor circuit
controller board
1 Check connection of connector (TH3,TH6/TH7) on
)
the outdoor controller circuit board.
Check connection of connector (CN3) on the
outdoor power circuit board.
Check breaking of the lead wire for thermistor
(TH3,TH6,TH7,TH8). Refer to "10-9. TEST POINT DIAGRAM".
2 Check resistance value of thermistor
(TH3,TH6,TH7,TH8) or check temperature by
microprocessor.
(Thermistor/TH3,TH6,TH7,TH8: Refer to "10-6. HOW
TO CHECK THE PARTS".) (SW2 on A-Control Service
Tool: Refer to "10-10. FUNCTION OF SWITCHES,
CONNECTORS AND JUMPERS".)
3 Replace outdoor controller circuit board.
Note: Emergency operation is available in
the case of abnormalities of TH3, TH6
and TH7. Refer to "10-8. EMERGENCY
OPERATION".
Open detection
−40°C or below
−40°C or below
−40°C or below
−27°C or below
12 Check outdoor fan.
3 Check airflow path for cooling.
4 Check if there is something which causes
temperature rise around outdoor unit.
(Upper limit of ambient temperature is 46°C.)
Turn off power, and on again to check if U5 is
displayed within 30 minutes.
If U4 is displayed instead of U5, follow the
action to be taken for U4.
5 Check resistance value of thermistor (TH8) or
temperature by microprocessor.
(Thermistor/TH8: Refer to "10-6. HOW TO CHECK THE PARTS".)
(SW2 on A-Control Service Tool: Refer to "10-10. FUNCTION OF
SWITCHES, CONNECTORS AND JUMPERS".)
6 Replace outdoor power circuit board.
7 Replace outdoor controller circuit board.
1 Open stop valve.
2 Check facility of power supply.
3 Correct the wiring (U
compressor. "10-9. TEST POINT DIAGRAM".
(Outdoor power circuit board).
4 Check compressor referring to "10-6. HOW TO
CHECK THE PARTS".
5 Replace outdoor power circuit board.
12 Check the installation conditions of discharge
temperature thermistor (TH4).
3 Check the coil of linear expansion valve.
Refer to "10-7. HOW TO CHECK THE COMPONENTS".
4 Check the connection or contact of LEV-A and
LEV-B on outdoor controller circuit board.
5 Check linear expansion valve.
Refer to "10-6. HOW TO CHECK THE PARTS".
1 Check or replace the DC fan motor.
2 Check the voltage of the outdoor circuit
controller board during operation.
3 Replace the outdoor circuit controller board.
(when the failure is still indicated even after
performing the action 1 above.)
40
judgment and action
Short detection
90°C or above
90°C or above
90°C or above
102°C or above
V
W phase) to
•
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