Repair, replace, maintain
How long does an AC unit last in Florida?
Ten to fifteen years is the working assumption in Central Florida, shorter than the national figure because the equipment runs close to year-round — roughly 3,452 cooling degree days a year at the nearest long-record station. In Longwood, where the median build year is 1979, most houses are on their third or fourth system.
Why Florida is shorter
Runtime, not calendar years
The number that shortens a Florida system's life is runtime, not age. A unit in a market with 3,452 cooling degree days does several times the work of the same unit in a temperate climate, and it does it in humidity, which is why DOE classifies Florida hot-humid on cooling hours and the relative humidity during them. Ten to fifteen years is what contractors here plan around.
What actually determines where in that band a particular system lands: whether the outdoor coil is kept clean, whether the return air is adequate, whether the condensate drain is maintained, and whether the system was correctly sized to begin with. An oversized system short-cycles, and short cycling is hard on a compressor.
- Working lifespan
- 10–15 years
- Cooling degree days
- ~3,452 a year
- Longwood median build year
- 1979
- 25th / 75th percentile
- 1973 / 1987
- Built 1970–89
- 66.5% of 4,962 parcels
What the appraiser's records show
A 1979 house is on its third or fourth system
Longwood's records make the point concretely. Across 4,962 improved residential parcels in tax district L1 the median build year is 1979, with a quarter built by 1973 and three quarters by 1987. At a 10–15 year replacement cycle, a 1979 house has been through three or four systems. So the year on the deed tells you about the duct and the floor plan; the install date on the equipment label tells you about the system.
Some subdivisions age together. Shadow Hill (1973–1980, 100% built 1970–89), The Landings (median 1982) and Devonshire (median 1973) were each built in tight windows, which means their equipment tends to reach end of life on the same schedule street by street. Subdivision build years.
What actually helps
Coil, return air, and booking the rebate in time
Two things extend the life of a system here more than anything sold as a premium feature: a clean outdoor coil, and adequate return air. Under Longwood's oak canopy the first is a recurring job rather than a one-off, and the City exempts owner-occupied single-family homes from tree removal permitting, so clearing what shades and fouls the condenser is unobstructed. What a maintenance visit should include.
And when the system does reach the end: book the Duke Home Energy Check before you buy, not after. The rebate is lost if the equipment is installed first. The sequence.
Sources
- NOAA 1991–2020 climate normals, Orlando station. https://www.ncei.noaa.gov/products/land-based-station/us-climate-normals
- U.S. DOE, 2023 Central Air Conditioner Standards FAQ. https://www1.eere.energy.gov/buildings/appliance_standards/pdfs/2023_CAC_Standards_FAQ_10-5-2022_Final.pdf
- Seminole County Property Appraiser CAMA extract (Parcels.csv, dated 5 September 2026), tax district L1 — Longwood; improved residential parcels, DOR codes 01 and 04. https://www.scpafl.org/
- City of Longwood FAQ: “Do I need a permit to remove a tree?”. https://longwoodfl.org/FAQ.aspx?QID=163
- Duke Energy, Home Energy Improvement — HVAC Replacement. https://www.duke-energy.com/home/products/home-energy-improvement/hvac-replacement
- Duke Energy Florida rebate application portal. https://www.dukeenergyrebates.com/florida/#/home
Figures are dated. Permit fees, rebate amounts and code cycles change — re-check the primary source before you rely on a number here.
Find the install date, not the build year
It is on the data plate of the outdoor unit. That one number changes every other answer about your system.