Check Code
Abnormal points and detection method
Cause
Judgment and action
29
OCH665B
U5
(4230)
Temperature of heatsink
Abnormal if heatsink thermistor (TH8)
detects temperature indicated below.
FRP71 ······································ 77°C
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
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.
U4
(TH3: 5105)
(TH6: 5107)
(TH7: 5106)
(TH8: 5110)
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 mode
of SW2. (PAC-SK52ST)
(Refer to "10-10 FUNCTION OF
SWITCHES, CONNECTORS AND
JUMPERS".)
1
Check connection of connector (TH3,TH6/TH7)
on the outdoor controller circuit board.
Check connection of connector (CN6) 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 (ATA only)".
1
Disconnection or contact failure
of connectors
Outdoor controller circuit
board: TH3, TH6/TH7
Outdoor power circuit board:
CN6
2
Defective thermistor
3
Defective outdoor controller
circuit board
(
)
U6
(4250)
Power module
Check abnormality by driving power module
in case overcurrent is detected.
(UF or UP error condition)
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
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. 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.
U8
(4400)
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
if;
• 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.
1
Failure in the operation of the
DC fan motor
2
Failure in the outdoor circuit
controller board
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.)
Thermistors
Open detection
Short detection
Symbol
Name
TH3
TH6
TH7
TH8
– 40°C or below
– 40°C or below
– 40°C or below
– 35°C or below
90°C or above
90°C or above
90°C or above
102°C or above
Thermistor <Liquid>
Thermistor <2-phase pipe>
Thermistor <Ambient>
Thermistor <Heatsink>
