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no
no
no
yes
yes
yes
yes
Replace PCB
Is DC voltage between both
ends of sensor near 5V or 0V?
Replace sensor
Is sensor resistance acceptable?
Replace sensor
Is sensor short-circuit or open-circuit?
check if the wiring is correct
according to wiring diagram
6) Sensor failure
no
reconnect
Relocate
if sensor is fixed well
re-wiring
yes
yes
yes
no
no
no
no
5) Communication error between indoor and outdoor units
Confirm commumication failure
according to the fault code list
re-wiring
change
defective parts
yes
Does indoor communication indicator flash?
Confirm the fault indicator is communication failure
Are communication wire S and supply wires L
and N properly connected? Grounded well?
if communication wire is broken
replace indoor PCB
if failure is eliminated
check if indoor/outdoor PCB fuse
and transformer are normal
replace outdoor PCB
no
yes
-248-
Troubleshooting