Carrier 38LUVH025N-1 Service Manual page 36

2.2 Indoor unit and outdoor unit communication protection error diagnosis and solution
Turn off the power supply, after 1 minute, connect the
power supply, turn on the unit with remote controller
Check the wiring between indoor unit and outdoor
unit. Is the connection of L, N, S and GND good?
Is the LED4(red) bright and LED1(yellow)
blinking on outdoor PCB?
The power supply for outdoor PCB is fail.
Check the wiring on outdoor PCB
comparing with wiring plate. Is the
connection good?
Correct the connection
The unit does not work normally
Yes
No
No
No
Yes
Yes
PART7, 3
Reconnect and retest
Replace indoor unit PCB
and repower
The unit does not
work normally
Replace the outdoor unit e-box
Replace outdoor e-box.