AH-AP24 (serv.man8). Troubleshooting guide of control circuit - Sharp Air Conditioner Service Manual (repair manual). Page 4

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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 ?