How Long Do Air Conditioners and Mini-Splits Last?

DOE publishes life-span ranges by equipment type. ENERGY STAR publishes a separate age for the repair-or-replace decision. Neither one is the BTU rating of the replacement.

Built by Jeremy Panasuk. Published October 6, 2026.

Quick answer: The U.S. Department of Energy’s Energy Saver 101 lists a room air conditioner (window or portable) at 10–15 years, a central air conditioner at 15–20 years, and a ductless mini-split at 12–15 years. ENERGY STAR’s repair-or-replace sheet uses a shorter decision line: under 10 years old, keep repairing an air conditioner or heat pump; over 10, it is time to look at replacement. A furnace or boiler on that sheet uses 15 years.

Two clocks, not one

Energy Saver 101 prints the life span next to the equipment type. A room unit, which that sheet defines as spot cooling from a window unit or a portable, is 10–15 years. Central air, the ducted system, is 15–20 years. A ductless mini-split is 12–15 years. An evaporative cooler on the same sheet is 15–20 years, and that cooler is not an air conditioner. DOE’s older Guide to Home Heating and Cooling says that if the heating or cooling system is over 15 years old, new equipment can cut the electric bill and improve efficiency. That 15-year sentence is a buying prompt in a 2010 guide. It is not the same number as Energy Saver 101’s central-air range, and it is not ENERGY STAR’s 10-year line. Quote the document you mean.

ENERGY STAR’s replace page says it may be time to call a contractor if the heat pump or air conditioner is more than 10 years old, and that a correctly installed ENERGY STAR unit can save up to 20 percent on heating and cooling costs. The repair-or-replace PDF puts the same 10 years in a table, with the furnace and boiler at 15, and it adds other columns: repeat problems, an extensive repair, cycling that seems excessive, and whether you are staying in the house. Two or more items in the replace column, that sheet says, means it is probably time to consider replacement. Age alone is one row, not the whole table.

Oversizing shortens the run you do get. ENERGY STAR’s clean heating and cooling page says oversized units tend to have shorter lives because short-cycling inflicts extra wear on the compressor. That is a reason to resize at replacement, not a reason to buy the same oversized cabinet again so it “lasts as long as the last one.”

Warranty length is on the warranty, not on this page

ENERGY STAR’s cooling-equipment consumer sheet lists “protect the validity of your equipment warranty” as one result of maintenance. It does not print a parts-year or a compressor-year. Those counts are in the warranty for the model you buy, and they often depend on registration and on professional installation. This page does not fill in a year the sheet left blank. Annual checkups are the maintenance step ENERGY STAR does publish: a contractor in the spring for cooling and in the fall for heating, on the maintenance checklist.

Worked example: do not copy a 12,000 BTU/hr nameplate

The room is 200 sq ft, 8 ft ceiling, 2 windows, average sun (factor 1.00), average insulation (factor 1.00). Those inputs go through this site’s room-load function.

Shell = 200 × 25 = 5,000 BTU/hr. Windows = 2 × 600 = 1,200. Subtotal = 6,200. Raw load = 6,200 × 1.10 = 6,820 BTU/hr. Rounded up to the next 500, the planning result is 7,000 BTU/hr.

ENERGY STAR’s room-air-conditioner chart puts 150 up to 250 sq ft at 6,000 BTU/hr before shade, sun, extra people, or a kitchen. A window unit whose nameplate says 12,000 BTU/hr is 12,000 ÷ 7,000 − 1 = 71 percent above this planning result. Replacing it with another 12,000 BTU/hr unit because “that’s what fit the window last time” copies the oversize. ENERGY STAR says a unit that is too large cools the room before it removes humidity. The cooling-equipment sheet says the same thing in buying language: do not assume the new system matches the old equipment, do not accept square footage alone, and ask the contractor for ACCA Manual J or a computer equivalent.

Use 7,000 BTU/hr as the planning number for this room, and the chart’s 6,000 BTU/hr if the replacement is a window unit and you have not applied the chart’s own adjustments. Use Manual J before a central or mini-split purchase. The age of the old unit does not change either arithmetic.

Common mistake

Treating “it is 12 years old” as an automatic replacement and “it is 9 years old” as an automatic repair, without the rest of ENERGY STAR’s table. A 9-year-old unit with repeat failures and an expensive repair is already in the replace column on more than the age row. A 12-year-old central unit that still meets the thermostat, with one minor repair, is inside DOE’s 15–20 year central range and still needs a judgment, not a slogan. The other mistake is ordering the replacement by the old BTU rating. Age answers whether to open the replacement conversation. The calculator, the ENERGY STAR chart, and Manual J answer what to buy.

Limits, and when to call a pro

These ranges are published life spans and a published decision table. They are not a prediction for one house, and this calculator is not a Manual J. Refrigerant in the old unit is an EPA disposal question, covered on how to dispose of an air conditioner. Do not cut the line to make the cabinet easier to haul. If the system is being changed out rather than repaired, have the contractor recover the charge and run the load calculation. A heat pump replacement has a heating load as well as a cooling load; that path is heat pump sizing.

Compiled with AI assistance from the sources below. Spot an error? Email jpanasuk@gmail.com.

Sources

U.S. Department of Energy, Energy Saver 101: Home Cooling — https://www.energy.gov/sites/default/files/2016/11/f34/HomeCooling101.pdf — accessed Oct 6, 2026.
U.S. Department of Energy, Guide to Home Heating and Cooling (DOE/EE-0338) — https://www.energy.gov/sites/prod/files/guide_to_home_heating_cooling.pdf — accessed Oct 6, 2026.
ENERGY STAR, Repair or Replace? — https://www.energystar.gov/ia/home_improvement/Replace_or_Repair.pdf — accessed Oct 6, 2026.
ENERGY STAR, When is it time to replace? — https://www.energystar.gov/saveathome/heating-cooling/replace — accessed Oct 6, 2026.
ENERGY STAR, Clean Heating and Cooling — https://www.energystar.gov/products/energy_star_home_upgrade/clean_heating_cooling — accessed Oct 6, 2026.
ENERGY STAR, Cooling Equipment Consumer Sheet — https://www.energystar.gov/ia/home_improvement/heat_cool/cooling_equipment.pdf — accessed Oct 6, 2026.
ENERGY STAR, Maintenance Checklist — https://www.energystar.gov/saveathome/heating-cooling/maintenance-checklist — accessed Oct 6, 2026.
ENERGY STAR, Room Air Conditioners — https://www.energystar.gov/products/room_air_conditioners — accessed Oct 6, 2026.
ACCA Manual J residential load calculation — https://www.acca.org/standards/technical-manuals/manual-j — accessed Oct 6, 2026.

Frequently asked questions

How long does DOE say a central air conditioner lasts?

Energy Saver 101 lists a central air conditioner life span of 15–20 years. The same sheet lists a room unit, window or portable, at 10–15 years, and a ductless mini-split at 12–15 years.

When does ENERGY STAR say to replace instead of repair?

ENERGY STAR’s repair-or-replace sheet says continue to repair an air conditioner or heat pump that is under 10 years old, and that it is time to replace when it is over 10 years old. A furnace or boiler on that sheet uses 15 years. The replace page also says to consider replacement when a heat pump or air conditioner is more than 10 years old.

Should the replacement match the old unit’s BTU?

No. ENERGY STAR’s cooling-equipment sheet says not to assume the new system is the same size as the old one, and not to accept a square-footage rule of thumb. Ask for a Manual J. This site’s calculator is only the planning pass before that.