Carrier 38QUS012D8S Service Manual page 140

2.4.4.19. J8 malfunction
Malfunction
conditions
Supposed causes
J8 display
J8 display
AC power input voltage
AC power input voltage
protection
protection
Check whether the power
Check whether the power
voltage is normal.
voltage is normal.
Yes
Measure whether outdoor
Measure whether outdoor
terminal voltage is normal？
terminal voltage is normal？
Yes
Measure whether the voltage
Measure whether the voltage
between L and N is normal？
between L and N is normal？
Yes
Measure whether input voltage
Measure whether input voltage
of bridge rectifier is normal？
of bridge rectifier is normal？
Yes
Measure whether the voltage
Measure whether the voltage
between P and N is normal
between P and N is normal
refer to the Appendix 3？
refer to the Appendix 3？
Yes
Replace the IPM board, If the IPM board
Replace the IPM board, If the IPM board
and main board is in a board, replace the
and main board is in a board, replace the
outdoor main PCB
outdoor main PCB
Electrical Control System
decision An abnormal voltage rise or drop is detected by checking the
specified voltage detection circuit.
Abnormal power supply

 Wiring mistake
 Faulty bridge rectifier

Faulty IPM
No
No
No
No
No
Yes
board
Restart the unit when the power
Restart the unit when the power
supply gets normal
supply gets normal
Check the wiring of
Check the wiring of
power wires well or
power wires well or
correctly
correctly
Check the wiring of
Check the wiring of
L and N well or
L and N well or
correctly
correctly
Check the wiring of
Check the wiring of
bridge rectifier well
bridge rectifier well
or correctly
or correctly
Check whether
Check whether
bridge rectifier is
bridge rectifier is
normal
normal
Yes
Replace the PFC module(If has)
Replace the PFC module(If has)
No
Check the wiring of
Check the wiring of
reactor or inductance
reactor or inductance
Yes
Check whether reactor
Check whether reactor
or inductance is normal
or inductance is normal
Troubleshooting
Reconnect it well
Reconnect it well
Reconnect it well
Reconnect it well
Reconnect it well
Reconnect it well
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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