Carrier 38QUS012D8S Service Manual page 133

2.4.4.11. P4 Malfunction
The troubleshooting is same as the "
2.4.4.12. J0 Malfunction
Malfunction conditions
Possible causes
J0 displayed
J0 displayed
Evaporator high temperature protection
Evaporator high temperature protection
Is the compressor operating?
Is the compressor operating?
Yes
Is the outdoor ambient
Is the outdoor ambient
temperature is higher than 30℃?
temperature is higher than 30℃?
No
Is the air-outlet blocked?
Is the air-outlet blocked?
No
Is the indoor fan running
Is the indoor fan running
normally?
normally?
Yes
Are the heat exchanger and
Are the heat exchanger and
filter dirty？
filter dirty？
No
Replace the indoor main
Replace the indoor main
PCB
PCB
Electrical Control System
IPM module protection
When evaporator coil temperature is more than 60°C, the unit stops. It
starts again only when the evaporator coil temperature is less than
54°C

Faulty evaporator coil temperature sensor

Dirty heat exchanger

Faulty fan

Faulty PCB
No
Yes
Stop the unit
Stop the unit
Clean the air-outlet
Yes
Clean the air-outlet
Refer to the solution for the
Refer to the solution for the
malfunction of the fan speed being out
malfunction of the fan speed being out
No
of control . Find the cause and resolve
of control . Find the cause and resolve
the problem
the problem
Clean the heat exchanger and filter
Yes
Clean the heat exchanger and filter
"
Is the connection
Is the connection
between T2 and The
between T2 and The
PCB is in working order?
PCB is in working order?
Have T2 and T2B been
Have T2 and T2B been
reversed?
reversed?
Yes
Is the resistance of T2
Is the resistance of T2
normal according to
normal according to
Appendix 1?
Appendix 1?
Yes
Troubleshooting
No
Correct the connection
Correct the connection
No
Replace the temperature sensor
Replace the temperature sensor
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