AU-A18 (serv.man8). Troubleshooting - 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 outdoor unit 

and terminal "N"  on the terminal board the 

power suuply 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.

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

Is the voltage

between terminal " N " and

" 2 " in the outdoor unit 

the power supply 

voltage ?

YES

NO