Kaisai KOU-12HDN1 Service Manual page 116

Troubleshooting
3. E3 malfunction (For 18K & 24K & 30K)
Communication malfunction in outdoor IC and DSP
Check whether the indicator lights LED1 on the main board is flashing
Check whether the connecting wiring between the IPM module and the CN4
on the main board is broken off
Disconnect the connecting wiring between the IPM module and the CN4 on the
main board, use the multimeter to measure the voltage between the IPM module
CN1 port's 3 and 4 pillar, check whether it is 5V, (the third pillar on the main board
Check whether the connecting wiring between the IPM module positive
pole and the CN12 on the power board is broken off
Check whether the connecting wiring between the IPM module negative
pole and the CN13 on the power board is broken off
Use the multimeter to measure whether the voltage between the CN12 and
the CN13 on the power board is between +（277V~345）V
Replace the power board
112
E3 display
No
No
labels +5V)
No
No
No
No
Yes
Replace the outdoor main board
Yes
Insert the connecting wiring well over
Yes
Replace outdoor main board
Yes
Insert the connecting wiring well over again
Yes
Insert the connecting wiring well over again
Yes
Replace the IPM module
MLCAC-UTSM-2010-10
again
Outdoor Units