Lennox LNINVE052 Service Manual page 71

7.IPM protection(H5), desynchronizing malfunction(H7), overcurrent of compressor phase current (P5) (AP1 below means
control board of outdoor unit)
Main detection points:
● Is voltage input within the normal range
● If the control board AP1 is well connected with compressor COMP? If they are loosened? If the connection sequence is correct?
● Heat exchange of unit is not good (heat exchanger is dirty and unit radiating environment is bad);
● If the system pressure is too high?
● If the refrigerant charging amount is appropriate?
● If coil resistance of compressor is normal? Is compressor coil insulating to copper pipe well?
● If the work load of unit is heavy? If radiating of unit is good?
Malfunction diagnosis process:
H5, H7 or P5 is
displayed after
turning on the unit
Measure if the voltage
input is within 180~265V
with AC voltmeter
(see fig 30)
The compressor
is well connected
with mainboard
AP1?
Heat exchanger is
blocked with dirt?
Check if system pressure
is too high?
Replace outdoor
mainboard AP1
68
N Repair power supply to make
the power voltage normal
Y
Adjust it properly
N
according to wiring
diagram 5.1
Y
Clean the heat exchanger
Y
to improve its performance
N
Y
N
Replace compressor
N
N
N
Adjust refrigerant
charging amount
Does the unit
work normally
N
The unit starts
Restart the unit
operation again
The unit starts
Restart the unit
operation again
The unit starts
Restart the unit
operation again
The unit starts
Restart the unit
operation again
Y
Installation and Maintenance
Service Manual
Y
Y
Y
Y
End