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65 

  During startup and operation of cooling and heating, the temperatures detected by the outdoor liquid pipe 

temperature sensor are used to determine sensor errors. 

 Faulty 

connector 

connection. 

 Faulty 

sensor. 

 Faulty 

PCB. 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

When abnormality indication starts again.

For safety reason and to prevent
component breakdown, always switch 
off the power before remove and 
connect the component.

Is the measured resistance of the outdoor liquid pipe 
temperature sensor matches the value specified in its 
characteristic chart?

Is the connector connection normal?

YES

YES

Check the outdoor discharge pipe temperature sensor:

Plug out connector from the outdoor unit PCB.
Measure the resistance of the outdoor discharge pipe
temperature sensor.

Check the connector connection:

Turn off the power.
Check the connector connection.

Connector poor contact.
Correct the connection.

Defect in outdoor unit PCB.
Replace the outdoor unit PCB.

Defect in outdoor discharge pipe
temperature sensor.
Replace the outdoor discharge pipe
temperature sensor.

NO

NO

66 

  The rotation speed detected by the Hall IC during fan motor operation is used to determine abnormal fan motor. 

  Operation stops due to short circuit inside the fan motor winding. 

  Operation stops due to breaking of wire inside the fan motor. 

  Operation stops due to breaking of fan motor lead wires. 

  Operation stops due to Hall IC malfunction. 

  Operation error due to faulty outdoor unit PCB. 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

YES 

NO

When abnormality indication starts again 

Turn power supply on and operate fan. 

Replace fan motor.

For safety reason and to prevent
component breakdown, always switch
 off the power before remove and
connect the component.

Does fan rotate smoothly?

Turn off power supply and rotate fan by
hand.  

Does it rotate?

CN-MTR2

(WHT)

IC19

3

5

1

10

14

16

W

U

V

FAN MOTOR

MS

CN-MTR1

PCB BOARD

5

4

3

2

1

C173

5V

R105

1k

C176

0.01μ

50V

G5

R111

1k

C177

0.01μ

50V

G5

R120

1k

C175

0.01μ

50V

G5

G5

+

YES 

NO

YES 

Turn off power supply and 
disconnect fan motor CN-MRT2 

Check resistance of the motor. 
Measure at fan motor connector
CN-MRT1 (1-2, 1-3, 2-3).  

Replace outdoor PCB.

NO

Replace fan motor.

YES

NO

U

W

V

Replace fan motor.

Replace fan motor.

NO

Replace outdoor PCB.

Stop the fan motor

YES

Is the resistance normal?

Check the rotation feedback output from  
fan motor’s CN-MTR1 output.
Rotate the fan motor manually (by hand)
while measure the voltage at PCB’s      
CN-MRT1
-

Between 1(+) and 5(-)

-

Between 2(+) and 5(-)

-

Between 3(+) and 5(-)

Use an inverter check to check on 
the power transistor on board. 

Do all 6 LED light turn ON and turn 
OFF periodically?

Does the voltage at each terminal
becomes 5 and 0Vdc repeatedly?

Connect it to PCB’s CN-MRT2 port.
Turn power ON and run the unit.

connector.

 

67 

  Indoor high pressure is detected when indoor heat exchanger is detecting very high temperature when the unit is 

operating in heating operation. 

  Phenomena: unit is stopping and re-starting very often in heating mode 

  Indoor heat exchanger thermistor 

  Clogged air filter or heat exchanger 

  Over-bent pipe (liquid side) 

 
Troubleshooting 
 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

NO

NO

YES

When abnormality indication starts again 

Check the indoor unit intake air filter 

Is the air filter dirty?

●  Clean the air filter

●  Clean the indoor unit heat exchanger

YES

Check the dust accumulation on the indoor unit heat exchanger  

Is the indoor unit heat exchanger dirty?

●  Defect in indoor pipe temperature
 thermistor
●  Replace the indoor pipe temperature
 thermistor

NO

Check the indoor pipe temperature thermistor:
●  Plug out connector (CN-TH) from the indoor unit PCB 
●  Measure the resistance of the indoor heat exchanger
 temperature 

thermistor

●  Check the piping & installation condition   
●  Replace piping / reinstall the unit if
 necessary

YES

Is the measured resistance of the indoor pipe temperature
thermistor matches the value specified in its characteristic
chart?   

For safety reason and to prevent
component breakdown, always switch
off the power before remove and
connect the component.  

68 

Error Code will not display (no Timer LED blinking) but store in EEPROM 
 
Malfunction Decision Conditions 

  Freeze prevention control takes place (when indoor pipe temperature is lower than 2°C) 

 
Malfunction Caused 

  Air short circuit at indoor unit 

  Clogged indoor unit air filter 

  Dust accumulation on the indoor unit heat exchanger 

  2/3 way valve closed 

  Faulty indoor unit fan motor 

 Refrigerant 

shortage 

(refrigerant leakage) 

  Clogged expansion valve or strainer 

  Faulty indoor pipe temperature sensor 

  Faulty indoor unit PCB 

 
Troubleshooting 
 

 

 
 
 
 
 

Check the air passage.

When abnormality indication starts again.

For safety reason and to prevent
component breakdown, always switch 
off the power before remove and 
connect the component.

Is there any short circuit?

YES

YES

YES

YES

YES

YES

YES

NO

NO

Check the indoor unit air filter.

Is the air filter dirty?

Is the indoor unit heat exchanger dirty?

Check if 2/3 way valve is closed?

Check if indoor fan motor operates normally?

Check if expansion valve or strainer clogged (ice formed)?

Does it conform to the sensor characteristic chart?

Check the indoor pipe temperature sensor.

Check the dust accumulation on the indoor unit heat 
exchanger.

Check for gas leakage, Is Oil oozing out from the 2/3 way 
valve?

●  Provide sufficient air passage.

●  Clean the air filter.

●  Clean the indoor unit heat exchanger.

●  Open the 2/3 way valve.

●  Replace the indoor unit PCB.

●  Replace the indoor pipe temperature
 sensor.

●  Reclaim and recharge with correct
 

amount of refrigerant.

●  Replace the indoor unit fan motor and/or
 

indoor unit PCB.

●  Repair the pipe flare or union nuts.
●  Reclaim and recharge refrigerant.

NO

NO

NO

NO

YES