Kaisai KOU-12HDN1 Service Manual page 122

Troubleshooting
10. P3 malfunction
Current protection of compressor
Judge 1: Check whether the input current of the power supply wire is more
than 20A (For 36K & 48K with 1 phase, it is 30A)
Check whether the refrigerant system is ok
Judge 2: Check whether the outdoor ambient temperature is too high
Judge 3: Check whether the outdoor unit is bad ventilation
Judge 4: Check whether the heat exchanger is dirty
Judge 5: The refrigerant pipe is blocked
118
P3 display
Yes
No
No
No
No
Replace outdoor main board
Yes
Yes
Make the outdoor unit ventilate well
Yes
Clean the heat exchanger
Yes
Let the refrigerant out, then use the high pressure
nitrogen or refrigerant to blow pipe, vacuumize and
charge the refrigerant again
MLCAC-UTSM-2010-10
Stop the unit
Outdoor Units