Lennox LICH4012021T431E-1, Service Manual

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Troubleshooting
Electrical Control System
142
2.4.4.11. P4 Malfunction
The troubleshooting is same as the “
IPM module protection
”
2.4.4.12. J0 Malfunction
Malfunction conditions
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
Possible causes
•
Faulty evaporator coil temperature sensor
•
Dirty heat exchanger
•
Faulty fan
•
Faulty PCB
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
temperature is higher than 30
℃
?
Is the outdoor ambient
temperature is higher than 30
℃
?
No
Correct the connection
Correct the connection
No
Is the connection
between T2 and The
PCB is in working order?
Have T2 and T2B been
reversed?
Is the connection
between T2 and The
PCB is in working order?
Have T2 and T2B been
reversed?
Is the resistance of T2
normal according to
Appendix 1?
Is the resistance of T2
normal according to
Appendix 1?
Replace the temperature sensor
Replace the temperature sensor
No
Yes
Yes
Stop the unit
Stop the unit
Yes
Is the air-outlet blocked?
Is the air-outlet blocked?
Are the heat exchanger and
filter dirty
？
Are the heat exchanger and
filter dirty
？
Is the indoor fan running
normally?
Is the indoor fan running
normally?
No
Yes
Clean the air-outlet
Clean the air-outlet
Replace the indoor main
PCB
Replace the indoor main
PCB
Clean the heat exchanger and filter
Clean the heat exchanger and filter
Yes
No
Yes
Refer to the solution for the
malfunction of the fan speed being out
of control . Find the cause and resolve
the problem
Refer to the solution for the
malfunction of the fan speed being out
of control . Find the cause and resolve
the problem
No
No