Lennox LIUH018021T431E-1 Service Manual page 110

0： No malfunction
1：P0 Overcurrent
2：Overpressure
3：Overload
4：Over speed
5：Startup malfunction
6：Lack of phase
7：DC voltage too low
8：Communication fault
9：Parameter fault
10：L3 Current limited
11：L5 Voltage limited
12: Target speed cannot be met during the static pressure calculation process.
For other models:
If the indoor fan speed is lower than 300 RPM for 50 seconds or more, it shuts off and restarts in 30 seconds.
If this happens 3 times, the unit stops and the LED displays the failure code.
Electrical Control System
Electrical Control Function
108