Carrier 619FB Service Manual page 33

7. Communication malfunction (E6)
Main detection points:
S Check if the wire is damaged or the polarity is mixed between terminals.
S Is the communication circuit of the indoor mainboard damaged?
S Is the communication circuit of the outdoor mainboard (AP1) damaged?
Malfunction diagnosis process:
Replace the
Yes
wire
Is the malfunction
No
eliminated?
Yes
Did the unit operate normally
before malfunction?
Yes
Is the polarity correct
between all terminals?
If the wiring is
damaged?
No
Check the malfunction
type with communication
malfunction detector
Malfunction of outdoor
Yes
communication circuit
No
Replace indoor
No
mainboard AP2
Fig. 36 – Troubleshooting
E6
No
Yes
No
Replace outdoor
mainboard AP1
Is the malfunction
eliminated?
Yes
End
33
Check the connection
wire according to the
wiring diagram.
If the connection wire
is connected well?
No
Reconnect the wire or
replace the connection
wire according to the
wiring diagram.
Is the malfunction
eliminated?
Yes