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29

The room is not cooled at all
or not cooled.
The compressor does not operate.

Measure resistances of TH1 and TH2.

The control circuit is normal.
   The compressor may be defective.
   The running capacitor may be defective.
   Refrigerant may be leaked.
   The outdoor fan motor may be defective.
   The outdoor fan motor capacitor may be defective.

Push the button "AUX." on 
the  indoor unit, for more than 5 sec.

Is the voltage

between terminal "N" and

"1" of the terminal board the

power supply voltage ?

Are the resistances

conformed Fig. 1 ?

Replace the thermistor ass'y with a new one.

NO

YES

YES

NO

Replace the PWB ass'y with a new one.

Using a tester, measure voltage at
the terminals on the terminal board.

100

80

60

40

20

0

-10

0

10

20

30

40

Resistance

Thermistor

Room temperature

Heat exchange

Color

Yellow

Orange

To measure the resistance, first remove 
the connector as shown at right.

Room temperature 

thermistor TH1

Tester

Connector

No. 3 to 4

No. 1 to 2

K

Heat exchange thermistor 
TH2 (orange)
25

°C resistance 15 K 

Room temperature 
thermistor TH1 (yellow)
25

°C resistance 10 K

Heat exchange 

thermistor TH2

Tester

4

1 CN4

30

The room is not cooled at all
or not cooled.
The compressor does not operate.

Measure resistances of TH1 and TH2.

The control circuit is normal.
   The compressor may be defective.
   The running capacitor may be defective.
   Refrigerant may be leaked.
   The outdoor fan motor may be defective.
   The outdoor fan motor capacitor may be defective.

Push the button "AUX." on 
the  indoor unit, for more than 5 sec.

Is the

voltage between

terminal of black lead

wire on the relay in the out door

unit and terminal "N"on the

terminal board the power 

supply voltage ?

Are the resistances

conformed Fig. 1 ?

Replace the thermistor ass'y with a new one.

NO

YES

YES

YES

NO

NO

Replace the PWB ass'y with a new one.

Replace the relay in the outdoor unit 
with a new one.

Using a tester, measure voltage at
the terminals on the terminal board.

Is the voltage

between terminal "N" and

"4"("2" ..... AU-A24DR) in the outdoor 

unit the power 

supply voltage ?

31

The room is not heated at all or not heated.
The compressor does not operate.

The control circuit board is normal.
   Refrigerant may be leaked.
   The running capacitor may be defective.
   The outdoor fan motor may be defective.
   The outdoor fan motor capacitor may be defective.
   The compressor may be defective.
   The thermistor may be defective.

   
   

Is the voltage

between terminal "N" and

"4"("1" ..... AY-AP18DR) of the 

terminal board the power 

supply voltage ?

NO

Replace the PWB ass'y with a new one.

Push the button of "AUX" on the  indoor 
unit, for more than 5 sec.

Using a tester, measure voltages at the 
terminals on the terminal board.

Select HEAT MODE with remote controller.
And then start operation.

Is the voltage

between terminal "N" and

"2" of the terminal board the

power supply voltage ?

Is the voltage

between terminal "N" and

"3" of the terminal board the

power supply voltage ?

YES

YES

YES

NO

NO

32

1

2

Capillary tube

3

Outdoor unit

Condenser

Evaporator

Indoor unit

Compressor

Flare coupling

Flare coupling

4

3-way
valve

2-way

valve

Accumulator

s

1

4

C

2

Capillary 
tube A

Capillary 
tube B

Capillary 
tube D
(Lower row)

Capillary 
tube C
(Upper row)

Accumulator

3

Strainer

Heating

Cooling

Outdoor unit

Condenser

Evaporator

Indoor unit

Reverse valve

Comp-

ressor

Flare coupling

Flare coupling

3-way

valve

2-way

valve

Silencer

Coil