AH-AP24 (serv.man8). Troubleshooting guide of control circuit - Sharp Air Conditioner Service Manual (repair manual). Page 5

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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