Carrier 42QHF012DS Service Manual page 60

Indoor / outdoor units communication error
Start: Power off , then Power on the
A/C by the Breaker. (reconnect the
power wire). Is it still displaying the
error code?
Yes
Check wiring on the outdoor and indoor
terminal follow the wiring diagram. Is all
connecting correctly?
Yes
Turn on all indoor unit by remote
controller. Is all indoor unit display
Yes
Turn off the all indoor units. Is IPM
power LED or operating LED lamp
On? Refer PIC2
Yes
"
Is main board"
lamp on? Refer PIC 3.
Yes
Is indoor units number correct? Check
on the outdoor check point . (2 for dual
zone, 3 for tri zone, 4 for qua zone).
Refer PIC 4.
No first time
No second time
Change outdoor unit PCB assembly(include
wiring) totally
No Reconnect the wiring
Reconnect the wiring
Measure Vs, is it moving
alternately between positive value
No and negative value? (Vs is the
voltage between S and N). Refer
PIC 1
Yes
No change IPM
Is the reactor connecting
No
well？
Yes
Change Outdoor Main PCB
A
60 / 78
A:
Is all the wiring between
No
terminal and Indoor PCB
Yes
Change the Indoor PCB
Power on by remote
controller, I
displaying the error code
No Reconnect the wiring
Trouble is solved
No
No
connect ok?
Yes
Is it still
after 3 minutes?
No