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1. Check temperature difference between intake and discharge air and operating current. 

Temp. Difference 

Temp. difference   :   approx. 0°C
Current                  :   less than 80% of 

rated current  

Temp. difference   :   approx. 8°C
Current                  :   less than 80% of 

rated current  

Temp. difference   :   less than 8°C
Current                  :   over the reated

current 

Temp. difference   :   over 8°C 

Operating Current 

• All amount of refrigerant leaked

out. Check refrigeration cycle.

• Refrigerant leakege

Clog of refrigeration cycle
Defective compressor 

• Excessive amount of refrigerant

• Normal 

Notice : 
Temperature difference between intake and discharge air depends on room air humidity. When the room air
humidity is relativery higher, temperature difference is smaller. When the room air humidity is relatively lower tem-
perature difference is larger. 

2. Check temperature and pressure of refrigeration cycle. 

Notice : 
1. The suction pressure is usually 4.5~6.0 kg/cm

2

G(Cooling) at normal condition. 

2. The temperature can be measured by attaching the thermometer to the low pressure tubing and wrap it with

putty. 

Suction pressure

Temperature

(Compared with

(Compared with

Cause of Trouble

Description

the normal value)

the normal valve)

Defective compressor

Current is low.

Defective 4-way reverse valve

Excessive amount of

High pressure does not quickly

Normal

refrigerant

rise at the beginning of 
operation.

Insufficient amount of 

Current is low.

Lower Higher

refrigerant 

(Leakage)

Clogging

Current is low.

High 

Higher  

Turn off Main Power

Turn on Main Power

Does "beeping" sound is made from the Indoor Unit?

Primarily, the operating condition of Micom is OK.

Check the voltage of power(About AC 220V/AC240V, 50Hz)

• Main power's voltage
• Voltage applied to the unit
• Connecting method of Indoor/Outdoor connecting cable
• Check PWB Ass'y

- Fuse
- Pattern damage
- Varistor(ZNR01N)

Check the connection housing for contacting

• Connector related to CN-POWER
• Connector related to CN-MOTOR
• Connector contacting of Outdoor Fan/Compressor
• Display PWB Ass'y Check

Check each load(Indoor/Outdoor Fan Motor,
Compressor, Stepping Motor) and contacting 
condition of related connector

NO

YES

(After 10 seconds)

Main PCB Board Operation Check

Items

• SMPS Transformer

(Indoor unit)
- Input Voltage
- Output Voltage

• IC04D(7805) Output

• IC01A(Reset IC)

OSL01B(8MHz)

• Replace P/Module

• Replace IC04D

• Replace faulty parts

- About AC220V/240V±10% - Check the power voltage
- About DC12V±115V
- About DC15V±2V (Motor Drive)

• DC +5V

• Voltage of Micom No. 36,

(DC +4.5V over) and Soldering condition.

Content

Remedy

Turn on Main Power

While the compressor has been stopped, the compressor does not

operate owing to the delaying function for 3 minutes after stopped.

Caused by other parts except the remote controller

Cause by the remote controller

When the mark(       ) is displayed in LCD screen, replace
battery.

Check the contact of CN-DI, 2 connector.

When the compressor stopped Indoor Fan is driven by a low speed.
At this point the wind speed is not controlled by the remote controller.
(When operated in the Sleeping Mode, the wind speed is set to the
low speed by force.)

Check DISP PWB Ass'y
- Voltage between CN DISP 

- 

: DC +5V

When the detect switch(double key) inside the remote 
controller door is fault, it is impossible to operate 
temperature regulating( / ) and wind speed selecting.

Check the connecting circuit between the remote controller
MICOM (No. 

61

) - R1 - TR - TR - LED - R2

Check point

• Check the connecting circuit between PIN 

-

Rø1L(1K) - Cø1L(680PF) - MICOM PIN

• Check Receiver Ass'y

Turn on Main Power

Operate "Cooling Mode(     )" by setting the desired temperature of the
remote controller is less than one of the indoor temperature by 1°C at least.

When in Air Circulation Mode, Compressor/Outdoor Fan is stopped.

Check the sensor for indoor temperature is attached as close as to be
effected by the temperature of Heat Exchanger(EVA).

When the sensor circuit for indoor temperature and connector are in bad
connection or are not engaged, Compressor/Outdoor Fan is stopped.

• Check R02H(12.1k), R04H(6.2k), Micom Pin 

26

, 

27

• Check the indoor temperature sensor is disconnected or not(About 10k

Ω / at 25°C).

Turn off Main Power

• Check the electrical wiring diagram of outdoor side.
• Check the abnormal condition for the component of

Compressor/Outdoor Fan Motor.

• Check the "open" or "short" of conmecting wires between indoor and

outdoor.

Check Relay(RY - COMP) for driving compressor.

• When the power(About AC220V/240V) is applied to the connecting wire

terminal support transferred to compressor, PWB Assembly is normal.

• Check the circuit related to the relay.

Check point

COMP ON

COMP OFF

Between Micom(No.

DC5V

DC0V

63) and GND

Between IC02M(No. 12)

Below DC 1V

About DC12V

and GND

(app)