Midea MOU-12HDN1-Q - Page 62

Troubleshooting MCAC-UTSM-2008-05
60 Outdoor Units
3. E3 malfunction
LED indicates E3
Communication malfunction in outdoor PCB
Check whether the indicator lights LED1 on the main board are flashing Replace the outdoor main board
Yes
Check whether the connecting wiring between the IPM module and
the CN4 on the main board is break off
Insert the connecting wiring well
over again
I
Yes
No
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 labels +5V)
No
Replace outdoor main board
Yes
No
Insert the connecting wiring well over again
Check whether the connecting wiring between the IPM module
positive pole and the CN12 on the power board is break off
Yes
No
No
Replace the IPM module
Use the multimeter to measure whether the voltage between the
CN12 and the CN13 on the power board is between
+（198V~254）V
Yes
Replace the power board
Check whether the connecting wiring between the IPM module
negative pole and the CN13 on the power board is break off
No
Insert the connecting wiring well over again
Yes