Carrier 42QFD048D8S Service Manual page 107

Check whether the power
Check whether the power
voltage is normal.
voltage is normal.
Measure whether outdoor
Measure whether outdoor
terminal voltage is normal？
terminal voltage is normal？
Measure whether the voltage
Measure whether the voltage
between L and N is normal？
between L and N is normal？
Measure whether input voltage
Measure whether input voltage
of bridge rectifier is normal？
of bridge rectifier is normal？
Measure whether the voltage
Measure whether the voltage
between P and N is normal
between P and N is normal
refer to the Index？
refer to the Index？
Replace the IPM board, If the IPM board and
Replace the IPM board, If the IPM board and
main board is in a board, replace the
main board is in a board, replace the
outdoor main PCB
outdoor main PCB
Note: For certain models, outdoor PCB could not be removed separately. In this case, the outdoor electric
control box should be replaced as a whole.
Yes
No
Yes
No
Yes
No
Yes
Yes

Restart the unit when the power supply
Restart the unit when the power supply
No
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 bridge
Check whether bridge
No
rectifier is normal
rectifier is 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
Yes
or inductance is normal
or inductance is normal
Troubleshooting
gets normal
gets normal
Reconnect it well
Reconnect it well
Reconnect it well
Reconnect it well
Reconnect it well
Reconnect it well
Replace the bridge rectifier
No
Replace the bridge rectifier
No
No

Reconnect the wiring
Reconnect the wiring
Replace reactor or
Replace reactor or
inductance
inductance