Lennox furnace and AC age by serial number
Lennox puts the year and month of manufacture in the third, fourth and fifth characters of the serial number. Type yours into this Lennox serial number lookup to read the Lennox manufacture date.
Where do I find the serial number?
Look for the data plate, a printed or stamped label that lists the model and serial numbers. On a furnace it is usually inside the front panel. On an outdoor AC or heat pump it is on the back or side of the cabinet.
How to read a Lennox serial number
A current Lennox serial has ten characters: four digits, one letter, then five digits. The first two digits are the factory, not the date. The year is the third and fourth digits. The letter that follows is the month.
- Used
- 1974 to present
- Format
- Plant code, year, month letter, sequence
- Example
- 1808B13467
- Months
- A to M, with I skipped. J is September, M is December.
Example, read
Check the brand first
A Carrier serial has the same shape but means something different: there the first four digits are the week and year. Always decode with the brand printed on the unit.
Where to find the serial number
Look for the data plate, a printed or stamped label that lists the model and serial numbers. On a furnace it is usually inside the front panel. On an outdoor AC or heat pump it is on the back or side of the cabinet.
Questions
My serial doesn't fit this pattern. Why?
Units made before 1974 used other formats that we don't decode yet. Check that you have typed a zero and not the letter O.
Is the manufacture date the same as the install date?
No. This is when the unit left the factory. It may have been installed weeks or months later.
What does the letter in a Lennox serial mean?
It is the month. A is January and the letters run to M for December, skipping I. So 5898G07568 reads as July 1998.
Does a Carrier serial read the same way?
No. A Carrier serial has the same shape, but its first four digits are the week and year. 1808B13467 is February 2008 as a Lennox serial and week 18 of 2008 as a Carrier one.
How old is my Lennox furnace or AC?
Read the third and fourth digits as the year and the letter after them as the month. Lennox years start at 1974, so each serial has only one possible year.
Can I look up a Lennox model number here?
No. A Lennox model number describes the kind of unit and its capacity, which matters for parts, not for age. We only decode the serial.