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Indication
Outdoor controller board
LED1 (Green) LED2 (Red)
3 blinking 1 blinking Abnormality of discharge
temperature (TH4) and Comp.
surface temperature (TH33)
2 blinking Abnormal high pressure (High
pressure switch 63H operated.)
Abnormal low pressure (Low
pressure switch 63L operated.)
3 blinking Abnormality of outdoor fan motor
rotational speed
Protection from overheat operation
(TH3)
4 blinking Compressor overcurrent
breaking(Startup locked)
Compressor overcurrent breaking
Abnormality of current sensor (P.B.) UH
Abnormality of power module
5 blinking Open/short of outdoor
thermistors (TH4, TH33)
Open/short of outdoor thermistors
(TH3, TH32, TH6, TH7 and TH8)
6 blinking Abnormality of heat sink
temperature
7 blinking Abnormality of voltage
4 blinking 1 blinking Abnormality of room temperature
thermistor (TH1)
Abnormality of pipe temperature
thermistor /Liquid (TH2)
Abnormality of tank temperature
thermistor
4 blinking Abnormality of pipe temperature
* Check code displayed on remote controller
** Refer to service manual for indoor unit.
OCH756
Check
Contents
code*
U2
U1
UL
U8
Ud
UF
UP
U6
U3
U4
U5
U9
P1
P2
P9
P8
51
Error
Inspection method
1 Check if stop valves are open.
2 Check if connectors (TH4, LEV-A) on outdoor con-
troller board are not disconnected.
3 Check if unit is filled with specified amount of refrig-
erant.
4 Measure resistance values among terminals on
indoor valve and outdoor linear expansion valve
using a multimeter.
1 Check if indoor/outdoor units have a short cycle on
their air ducts.
2 Check if connector(63H) (63L) on outdoor controller
board is not disconnected.
3 Check if heat exchanger and filter is not dirty.
4 Measure resistance values among terminals on lin-
ear expansion valve using a multimeter.
1 Check the outdoor fan motor.
2 Check if connector (TH3) (63HS) on outdoor control-
ler board is disconnected.
1 Check if stop valves are open.
2 Check looseness, disconnection, and converse con-
nection of compressor wiring.
3 Measure resistance values among terminals on com-
pressor using a multimeter.
4 Check if outdoor unit has a short cycle on its air duct.
5 Check leakage of refrigerant.
1 Check if connectors (TH3, TH32, TH4, TH33 and
TH7/6) on outdoor controller board and connector
(CN3) on outdoor power board are not disconnected.
2 Measure resistance value of outdoor thermistors.
1 Check if indoor/outdoor units have a short cycle on
their air ducts.
2 Measure resistance value of outdoor thermistor(TH8).
1 Check looseness, disconnection, and converse con-
nection of compressor wiring.
2 Measure resistance value among terminals on com-
pressor using a multimeter.
3 Check if power supply voltage decreases.
4 Check the wiring of CN52C.
5 Check the wiring of CNAF.
1 Check if connectors on indoor controller board are
not disconnected.
2 Measure resistance value of indoor thermistors.
1 Check if indoor thermistors(TH2 and TH5) are not
disconnected from holder.
2 Check if stop valve is open.
3 Check converse connection of extension pipe. (on
plural units connection)
4 Check if indoor/outdoor connecting wire is connected
correctly. (on plural units connection)
Detailed
reference
page
P.24
P.24
P.27
P.25
P.27
P.27
P.28
P.27
P.25
P.24
P.25
P.25
P.26–
P.27
**
**
**
P.29
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