Kaisai KOU-12HDN1 Service Manual page 120

Troubleshooting
8. P1 malfunction
High pressure protection
Judge 1: Whether the wiring between the high pressure switch and main
control board is connected well or correctly
Judge 2: Whether the high pressure switch is broken
Method: Short connect the high pressure switch socket, check
whether the system can run normally
Check whether the refrigerant system is ok
Judge 3: Check whether the outdoor ambient temperature is too high
Judge 4: Check whether the outdoor unit is bad ventilation
Judge 5: Check whether the heat exchanger is dirty
Judge 6: Check whether the refrigerant pipe is blocked
Replace outdoor main board
116
P1 display
Yes
No
No
No
No
No
No
Connect it well
Yes
Replace high pressure switch
Yes
Stop the unit
Yes
Make the outdoor unit ventilate well
Yes
Clean the heat exchanger
Let the refrigerant out, then use the high pressure
Yes
nitrogen or refrigerant to blow pipe, vacuumize and
charge the refrigerant again
MLCAC-UTSM-2010-10
Outdoor Units