Carrier 38QUS012D8S Service Manual page 127

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F0 displayed
Current protection of compressor
Current protection of compressor
Was the protection activated
Was the protection activated
in standby?
in standby?
No
Is the power voltage is
Is the power voltage is
normal?
normal?
Yes
Is outdoor terminal voltage
Is outdoor terminal voltage
normal？
normal？
Yes
Is the voltage between L and
Is the voltage between L and
N is normal？
N is normal？
Yes
Is the input voltage of the
Is the input voltage of the
bridge rectifier is normal？
bridge rectifier is normal？
Yes
Is the current normal？
Is the current normal？
No
Is the voltage between P and
Is the voltage between P and
N normal refer according to
N normal refer according to
Appendix 3？
Appendix 3？
Yes
Is the outdoor ambient
Is the outdoor ambient
temperature is higher than
temperature is higher than
50℃?
50℃?
No
Is the outdoor unit
Is the outdoor unit
ventilation functioning
ventilation functioning
properly?
properly?
Yes
Is the outdoor fan running
Is the outdoor fan running
properly?
properly?
Yes
Is the heat exchanger dirty?
Is the heat exchanger dirty?
No
Replace outdoor main
Replace outdoor main
board. Does a problem still
board. Does a problem still
exist?
exist?
No
Is system pressure too high?
Is system pressure too high?
No
Check whether the refrigerant
Check whether the refrigerant
system is running normally
system is running normally
Electrical Control System
Restart the unit when the power
Restart the unit when the power
No
Is the power wiring
Is the power wiring
No
wired correctly?
wired correctly?
Are L and N wired
Are L and N wired
No
properly?
properly?
Is the bridge
Is the bridge
No rectifier wired
rectifier wired
properly?
properly?
Yes Replace the outdoor main PCB
Replace the outdoor main PCB
No
Yes Stop the unit
Stop the unit
Ensure that the outdoor unit
Ensure that the outdoor unit
No
ventilate is working properly
ventilate is working properly
Refer to the solution to the
Refer to the solution to the
malfunction of fan speed being out
malfunction of fan speed being out
No
of control. Find the cause and
of control. Find the cause and
resolve the issue
resolve the issue
Yes Clean the heat exchanger
Clean the heat exchanger
Recycle the overcharged
Recycle the overcharged
Yes
refrigerant
refrigerant
supply returns to normal
supply returns to normal
Reconnect the
Reconnect the
power wiring
power wiring
Reconnect L and N
Reconnect L and N
Reconnect the
Reconnect the
bridge rectifier
bridge rectifier
Is the bridge rectifier
Is the bridge rectifier
functioning normally?
functioning normally?
Yes
Replace the PFC module (if this has not
Replace the PFC module (if this has not
been done already)
been done already)
No
Is the wiring of the
Is the wiring of the
reactor or inductance
reactor or inductance
properly wired?
properly wired?
Yes
Are the reactor and
Are the reactor and
inductance functioning
inductance functioning
normally
normally
Yes
Troubleshooting
Yes
Replace the bridge
Replace the bridge
No
rectifier
rectifier
Reconnect the
Reconnect the
No
wiring
wiring
Replace reactor or
Replace reactor or
No
inductance
inductance
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