Lennox LIUH018021T431E-1 Service Manual page 152

2.4.4.20. P2 malfunction
Malfunction
conditions
Supposed causes
Check if the air flow system
of indoor and outdoor units
are obstructed?
No
Turn off the power supply and turn
it on 10 minutes later.
Yes
Check if the temperature
of compressor Top
Is more than 90℃？
Yes
Check if the refrigerant
system
is normal?
Yes
Replace the outdoor control PCB.
Electrical Control System
decision
If the sampling voltage is not 5V, the LED will display the failure.
Faulty overload protector
●
Wiring mistake
●
System leakage or block
●
Faulty PCB
●
Clear up the air inlet and outlet or the heat
Yes
exchanger of indoor and outdoor units.
Check if all the connection, especially
No the connection of OLP (Over Load
No
Repair the refrigerant
Protector) sensor is good.
Yes
Measure the resistance
between the two ports of
the OLP. Is it zero?
Yes
system .
Troubleshooting
No Correct the connection.
No Replace the OLP.
Replace the outdoor control PCB.
150