When to Replace an AC Unit
Replace an air conditioner when it's past about 12 to 15 years and needs a big repair, when it uses R-22 refrigerant and has a leak, or when comfort and bills have clearly slipped. Smaller repairs are usually worth doing.
By Suraj Jha · Updated 2026-10-25
The decision at a glance
| Situation | Usually |
|---|---|
| Under 10 years, small repair (capacitor, contactor, fan motor, drain line) | Repair |
| Under 10 years, compressor or coil failure | Check warranty, then usually repair |
| 10–15 years, small repair | Repair, start budgeting |
| 10–15 years, compressor or coil failure | Compare with replacing; often replace |
| Over 15 years, any major repair | Replace |
| R-22 system with a leak or compressor failure | Replace |
1. How old is it?
Most central air conditioners last 12 to 17 years. Find the age from the serial number on the outdoor unit’s rating plate with our HVAC age lookup. If you also have a furnace or air handler, check its age too: the indoor coil usually sits on top of it, and replacing them together is often the better job.
2. What refrigerant does it use?
Check the rating plate for the refrigerant line:
- R-22 (HCFC-22): standard until about 2010. No longer produced or imported in the US since 2020, so only recycled supplies remain and recharges are expensive. A major leak on an R-22 system is usually the end.
- R-410A: the standard from 2010 until 2025. Still serviceable, though new systems now use lower-impact refrigerants.
- R-454B or R-32: used in new systems from 2025 onward.
More detail in our R-22 phase-out guide.
3. What would the repair cost, relative to a new system?
The common rule: if the repair costs more than half the price of replacement, replace. For a system past about 10 years, many contractors use a lower threshold, around a third, because the next failure is closer.
Compressor and outdoor-coil replacements are the expensive ones. Capacitors, contactors, fan motors and drain-line clearing are routine at any age.
4. How much would a new unit save?
Air conditioner efficiency is rated in SEER (and, since 2023, SEER2, a stricter test that gives lower numbers for the same equipment). Rough savings on the energy used for cooling:
| Old system | New system | Approximate saving |
|---|---|---|
| 10 SEER (around 2005 or older) | 15 SEER | ~33% |
| 13 SEER (2006–2015 minimum) | 16 SEER | ~19% |
| 14 SEER | 18 SEER | ~22% |
In hot climates with long cooling seasons, that’s significant; in mild climates, less so.
5. Is comfort the real problem?
Hot rooms, clammy air and short run cycles are often caused by duct problems or by an oversized system rather than the age of the equipment. A replacement is the best chance to fix them: ask for a load calculation (Manual J), a duct check, and consider a two-stage or variable-speed system for better humidity control.
Before you buy
- Get two or three quotes, and compare the scope as well as the price: coil, line set, thermostat, permit, haul-away.
- Make sure the outdoor unit and indoor coil are an AHRI-matched combination.
- Register the new equipment right away to get the longer parts warranty.
- Ask about utility rebates and current incentives, particularly for heat pumps.
Frequently asked questions
How old should an AC be before replacing it?
Central ACs usually last 12 to 17 years. Age alone isn't a reason to replace a unit that cools well, but past about 12 years it's worth planning, and a major repair at that age usually tips the decision.
Should I replace my AC if it uses R-22?
If it's working, you can keep using it. If it has a leak or a compressor failure, replacing is usually smarter, because R-22 is no longer produced and recharging is expensive.
How much will a new AC save on electricity?
It depends on the old and new efficiency. Going from a 10 SEER unit to a 15 SEER unit cuts the energy used for cooling by about a third (1 − 10/15). From 13 to 16 SEER, the saving is closer to a fifth.
Do I have to replace the indoor coil too?
Usually, yes, when replacing an older system, and almost always if the refrigerant type changes. A mismatched coil can reduce efficiency and may void the new unit's warranty.
Should I replace my AC with a heat pump?
Worth pricing. A heat pump replaces the AC and also provides efficient heating, which can cut winter bills if you heat with electric resistance, propane or oil. In very cold climates, cold-climate models or dual-fuel systems are the usual choice.
Next steps
Look up the age of your furnace and air conditioner
More about air conditioners and heat pumps
Browse all guides.