Lennox Allied Air Enterprise A97DSMV Installation Instructions Manual page 64

Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover
E409 LSOM - Compressor low voltage. Secondary voltage is below 18VAC. After 10 minutes,
operation is discontinued. Clears the code after voltage
is higher than 20VAC for 2 seconds or after power
reset.
Page 64 of 73 Issue 2241 507029-05