Lennox LI018CI-180P432 Service Manual page 53

4.Diagnosis for failure start up malfunction (AP1 below is control board of outdoor unit)
Main detection point:
● If the compressor wiring is correct?
● If the stop time of compressor is enough?
● If the compressor is damaged?
● If the refrigerant charging is too much?
Malfunction diagnosis process:
well connected and connection sequence
50
Energize the unit
and start it
If the stop time of compressor
is more than 3min?
Y
If the compressor wire COMP(UVW) is
is correct
Y
If the refrigerant charging is
too much?
Y
Charge the
refrigerant according
to service manual
Does the unit start
up normally?
N
Replace control board AP1
If malfunction is
removed?
N
Replace the
compressor
End
If the stop time is not enough and the
N
high and low pressure of system is not
balance , please start it after 3min
Improve the connection situation
of control board AP1 and
N
compressor COMP, connect it
with wiring diagram
Does the unit start
up normally?
N
Y
Service Manual
Installation and Maintenance