Panasonic CS-MS9SD3H Service Manual page 66

13.5.24 F99 (DC Peak Detection)
Malfunction Decision Conditions
During startup and operation of cooling, 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 F99 indication happens
Reset the error code and turn on the unit
again
Is there a sound when compressor starts?
Is compressor vibration even?
Is there no change even if all refrigerant
is discharged?
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
Are the compressor's winding resistance
(U-V, V-W or U-W) shorted?
NO (Compressor stops)
YES
NO (Quite a lot of vibration at
start operation)
YES
NO (Normal)
YES (Stops after 2, 3 seconds
of noise during operation)
NO (Normal)
YES
For safety reason and to prevent component
breakdown, always switch off the power
Caution before remove and connect the component.
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Outdoor electronic circuit defect due to
power transistor short
Replace the outdoor unit PCB
Amplification IC defect
Diode defect
Defect in microcontroller
Replace the outdoor unit PCB
Excessive amount of refrigerant
Compressor defective due to
mechanical locked
Replace compressor
Compressor defective due to winding
shorted
Replace compressor