Did a house with three Heil A/C s guy said the house was built in 2004 I had the age of units at 6 years old I’m second guessing myself after that. The serial #L010682171
serial#L010571269
serial#L010301432
Hi Don
You are right, in my book it give me 2001. L01 =2001
Jeannot
Yep…2001, in March, May, and June