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Check Code
Abnormal point and detection method
Open/short of outdoor unit thermistors
(TH3, TH6, TH32, TH34, TH6, TH7, and TH8)
Abnormal if open or short is detected
during compressor operation.
Open detection of thermistors TH3, TH32
and TH6 is not detected 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 mode of
SW2. (PAC-SK52ST) (Refer to "8-7.
OUTDOOR UNIT OPERATION
MONITOR FUNCTION".)
U4
Symbol
TH3
Thermistor <Liquid>
TH32
Thermistor <Inlet Water>
TH6
Thermistor <Plate HEX liquid>
TH7
Thermistor <Ambient>
TH8
Thermistor <Heat Sink>
Temperature of heat sink
Abnormal if heat sink thermistor (TH8)
detects temperature indicated below.
W50VHA2 ••••••••••••• 77°C
U5
Power module
Check abnormality by driving power module
in case overcurrent is detected.
U6
(UF or UP error condition)
Too low superheat due to low discharge
temperature
Abnormal if discharge superheat is
continuously detected −15: or less for
3 minutes even though linear expansion
valve has minimum open pulse after
U7
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;
• 100 rpm or below detected continuously
for 15 seconds at 20: or more outside
air temperature
• 50 rpm or below or 1500 rpm or more
detected continuously for 1 minute.
OCH605A
Case
1 Disconnection or contact failure
of connectors
(
Outdoor controller circuit board:
TH3, TH32, TH34, TH6/TH7
Outdoor power circuit board:
CN6
2 Defective thermistor
3 Defective outdoor controller
circuit board
Thermistors
Name
1 The outdoor fan motor is
locked.
2 Failure of outdoor fan motor
3 Air flow path is clogged.
4 Ambient temperature is high.
5 Defective thermistor
6 Defective input circuit of
outdoor power circuit board
7 Failure of outdoor fan drive
circuit
1 Defective outdoor power cir-
cuit board
2 Decrease of power supply voltage
3 Looseness, disconnection or
reverse of compressor wiring
connection
4 Defective compressor
1 Disconnection or loose
connection of discharge
temperature thermistor (TH4)
2 Defective holder of discharge
temperature thermistor
3 Disconnection or loose connec-
tion 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
17
Judgment and action
1 Check connection of connector (TH3, TH32,
TH34, TH6/TH7) on the outdoor controller circuit
)
board. Check connection of connector (CN6) on
the outdoor power circuit board. Check the lead
wire for thermistor (TH3, TH32, TH34, TH6, TH7,
TH8). Refer to "8-6. TEST POINT DIAGRAM".
2 Check resistance value of thermistor (TH3,
TH32, TH34, TH6, TH7, TH8) or check tem-
perature on LED display. (Thermistor/TH3,
TH32, TH34, TH6, TH7, TH8: Refer to "8-5.
HOW TO CHECK THE COMPONENTS".)
(SW2: Refer to "8-7. OUTDOOR UNIT
OPERATION MONITOR FUNCTION".)
3 Replace outdoor controller circuit board.
Open detection
Short detection
−40°C or below
−40°C or below
102°C or above
−40°C or below
−40°C or below
−35°C or below
102°C or above
12 Check outdoor fan.
3 Check air flow path for cooling.
4 Check if there is something which causes
temperature rise around outdoor unit.
(Upper limit of ambient temperature is 46:.)
Turn off power, and on again to check if U5 is
displayed within 30 minutes. If U4 is displayed
instead of U5, refer to check code U4.
5 Check resistance value of thermistor (TH8) or tem-
perature by microcomputer. (Thermistor/TH8: Refer
to "8-5. HOW TO CHECK THE COMPONENTS".)
(SW2: Refer to "8-7. OUTDOOR UNIT
OPERATION MONITOR FUNCTION".)
6 Replace outdoor power circuit board.
7 Replace outdoor controller circuit board.
1 Replace outdoor power circuit board.
2 Check facility of power supply.
V
W phase) to
3 Correct the wiring (U
•
•
compressor. Refer to "8-6. TEST POINT
DIAGRAM" (Outdoor power circuit board).
4 Check compressor referring to "8-4. HOW
TO CHECK THE PARTS".
12 Check the installation conditions of dis-
charge temperature thermistor (TH4).
3 Check the coil of linear expansion valve.
Refer to "8-5. 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 "8-4. 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 remedy 1 above.)
90°C or above
90°C or above
90°C or above
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