Panasonic CS-E18SD3UAW service manual - Page 95

15.5.24 F99 (DC Peak Detection) Malfunction Decision Conditions During startup and operation of cooling and heating, when inverter DC peak data is received by the outdoor internal DC Peak sensing circuitry. Malfunction Caused  DC current peak due to compressor failure.  DC current peak due to defective power transistor(s).  DC current peak due to defective outdoor unit PCB.  DC current peak due to short circuit. Troubleshooting When abnormality indication starts again Reset the error code and turn on the unit again Is there a sound when compressor starts? NO (Compressor stops) Outdoor electronic circuit defect due to power transistor short Replace the outdoor unit PCB YES Is compressor vibration even? YES NO (Quite a lot of vibration at start operation) Amplification IC defect Diode defect Defect in microcontroller Replace the outdoor unit PCB Is there no change even if all refrigerant is discharged? NO (Normal) Excessive amount of refrigerant YES (Stops after 2, 3 seconds of noise during operation) Check the compressor winding resistance: Turn off the power and disconnect the harnesses U, V and W Measure the winding resistance between U-V, V-W and W-U Caution For safety reason and to prevent component breakdown, always switch off the power before remove and connect the component. Are the compressor's winding resistance (U-V, V-W or U-W) shorted? YES NO (Normal) Compressor defective due to mechanical locked Replace compressor Compressor defective due to winding shorted Replace compressor 95