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5 - 41

The intake temperature (ambient temperature) of the indoor unit is 
above 36°C.

3-6

Prevent air short 
circuit

3-7

Yes

No

The filter of the indoor unit is clogged.

3-7

Clean the filter

3-8

Yes

No

The fan of the indoor unit is broken or the fan motor is faulty.

3-8

Replace the indoor 
fan (motor)

4-1

Yes

No

Is the outdoor unit’s electronic control valve operating correctly? 
(Check for debris clogging the electronic control valve, a problem 
with the electronical coil and/or the control PC board.)

4-1

4-3

Repair the electronic 
control valve of the 
outdoor unit

Yes

No

If an alarm is occurred with the high pressure below 3.80 MPa, 
with the pressure measured as displayed by the manifold gauge, 
check the check valve in the compressor discharge line. 
Are these checking finished without fail?

4-3

4-4

Replace the check
valve in the
compressor
discharge line

Yes

No

The electronic control valve is faulty. 
In systems where the solenoid valve kits and the ice thermal 
storage tank are connected, check these solenoid valves.

4-4

Replace the 
electronic control 
valve and/or 
solenoid valve.

5-1

Yes

No

The indoor unit's expansion valve is operating correctly.
(check for debris clogging the valve, a problem with the electronical 
coil and/or the control PC board)

4-2

4-3

Repair the expansion
valve of the indoor
unit

Yes

No

3 Problem

around the
heat
exchanger

4 Blockage

in the
refrigerant
circuit

Error occurs when the system is operating in cooling mode.

5-1

5-3

5-2

Yes

No

An alarm is occurred with the high pressure at 3.80 MPa, with the 
pressure measured either as displayed by the monitoring software 
or with a manifold gauge, at which time the temperature of liquid in 
the outdoor unit’s heat exchanger is detected to be at the 
temperature of the outside air.

5-3

5-5

Contact the service
representative

Yes

No

An alarm is occurred with the high pressure at 3.80 MPa, with the 
pressure measured either as displayed by the monitoring software 
or with a manifold gauge, at which time the temperature of liquid in 
the indoor heat exchanger is detected to be at room temperature 
(intake temperature).

5-4

5-5

Contact the service
representative

Yes

No

The system may be overcharged. Check how much refrigerant was added during installation.
When a system is inspected for airtightness, it is seldom that enough nitrogen has been 
expelled, so some remains in the circuit. 
In this case, it is necessary to collect the refrigerant and then recharge the system.

5-5

Error occurs when the system is operating in heating mode.

5-2

5-4

5-5

Yes

No

5 Overcharg-

ing

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1-1

1-4 : Single-phase model 
1-2 : 3-phase model

3-1 : Single-phase model 
2-1 : 3-phase model

Check for open circuit and the voltage at the breaker. 
if a problem is found, fix it and check again.

Yes

No

Turn the power back on and check again. 
Is the alarm triggered again?

1-4

2-1

Power wiring N-phase is connected.

Power wiring L2 and N are reverse connected.

The connector CN-PRY2 on the outdoor CR PC board is 
connected properly (locked).

1-2

1-3

4-1

Yes

No

Correct wiring

1-3

Yes

No

Correct wiring

1-4

Yes

No

1 Check 

the power 
supply &
the wiring

Are the wires (RE1, RE2) from the reactor firmly installed?

3-1

3-2

Correct wiring

Yes

No

Turn the power back on and check again. 
Is the alarm triggered again?

4hp, 5hp: 

Common in RE1 and RE2

Plug-in type

6hp: Fastening screw type

*

3-2

Replace the outdoor 
unit HIC PC board. 

4-1

Yes

No

3 Check the

outdoor
unit HIC 
PC board

2 Check the

outdoor
unit CR
PC board

There may be a instantaneous blackout failure. 
If there is nothing abnormal, see what happens.

RE1*

RE2*

4-1

4 Final check

Instantaneous blackout

•

Note : The work involved in diagnosing each of the items is extremely dangerous, so turn the power off at the breaker before

performing the tests.

Zero-cross (waveform input of power supply) error

•

DC voltage charge failure

•

Is the voltage on each of the 
terminal boards within +10% 
of the rated voltage?

RE1

RE2

Correct wiring 
(connector)

3-1

Yes

No

CN-PRY2

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5 - 43

Detection is performed only in the test run. When once detected or the test run finished without any error, 
the second detection will not be done. 
In case of forgetting to open a valve, P04 (high-pressure switch operational alarm) is occasionally preceded due to the 
following conditions.

The status of small temperature change of the oprating indoor unit continues for 3 minutes even after 5-minute to 
15-minute since the cooling test run has started.

•

The status of small temperature change of the oprating indoor unit continues for 3minutes even after 7-minute to 
15-minute since the heating test run has started.

•

1-1

2-1

Yes

No

1 Service 

valve

Open the service 
valve

2-1

2 Adjustment 

to 
refrigerant 
change

3 Blockage 

in 
refrigerant 
circuit

3-1

Avoid clogging

3-2

Yes

No

Are the tubes clogged?

Not additional refrigerant charged

3-1

Yes

No

Additional 
refrigerant charge

3-2

3-3

Replace the 
electronic control 
valve

Yes

No

Is the outdoor unit’s electronic control valve operating correctly? 
(Check for debris clogging the electronic control valve, a problem 
with the electronical coil and/or the control PC board.)

3-3

As the second detection is not done, restart and see what happens if there is no error.

Service valve inside the outdoor unit closed

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5 - 44

1-1

3-1

2-1

Yes

No

1 System 

configuration

Is the indoor EEPROM setting, item code 0B, on the indoor unit’s 
control PC board set to 0001?

2-1

After correcting the
setting, 3-1

4-1

Yes

No

2 Indoor unit’s

EEPROM
setting

It is judged an error whenever the outdoor unit receives the signal “O

2

 Alarm Occurred” from the indoor unit.

•

With the indoor unit's EEPROM setting (item code 0B) set to 0001, the EXCT input was shorted.

•

Is an O

2

 sensor being used?

Correct wiring

4-1

Yes

No

Is the indoor EXCT socket (wire) shorted?

3-1

3

4

Indoor EXCT
wiring

4-3

4-2

Yes

No

Is the alarm triggered if the indoor EXCT socket (wire) is 
disconnected, and the power is reset?

Since there is no error, see what happens.

4-1

4-2

4-3 Indoor unit control PC board error

replace PC board.

Indoor unit’s
control 
PC board

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