$4,000–$9,000 to replace a 3-ton central AC on existing ducts in the US, installed — $6,200 typical. A 2-ton system runs $3,350–$7,500, a 5-ton $5,600–$12,600, and a high-efficiency variable-speed 3-ton up to $13,500.
3-ton central AC on existing ducts: $4,000–$9,000, $6,200 typical
Size comes first. A 3-ton system cools about 1,600–2,000 sq ft and costs $4,000–$9,000; each step up in tonnage adds equipment cost, and a 5-ton system runs $5,600–$12,600. A proper load calculation (Manual J) stops a contractor from simply matching the old unit, which may be oversized.
Efficiency is next. The federal minimum for a new split AC is 13.4 SEER2 in the North. In the Southeast and Southwest it is 14.3 SEER2 for units under about 3.75 tons, and 13.8 SEER2 for bigger units. Moving to a 17+ SEER2 two-stage unit costs $5,800–$11,500 on a 3-ton system, and a 20+ SEER2 variable-speed system runs $7,500–$13,500.
Access and condition matter too: an attic air handler, a rooftop condenser, a new line set or a cracked pad all add labor. Labor is usually 40–60% of the bill.
02
What a replacement quote should include
A complete quote covers the outdoor condenser, a matched indoor coil (or air handler), refrigerant, a new or flushed line set, the pad, the electrical disconnect and whip, removal of the old unit, the permit, and startup with a charge check.
Ask for the exact model numbers and the matched SEER2 rating from the AHRI directory. A new condenser on an old indoor coil is a common shortcut, and with the newer refrigerants the coil has to match.
03
The refrigerant change and what it does to your bill
New split AC and heat pump systems are now built for A2L refrigerants (R-454B or R-32), and makers no longer build complete R-410A systems. A new outdoor unit needs a matching new indoor coil, which is why a condenser-only swap is rarely offered anymore.
An EPA rule finalized in May 2026 (in effect since July 27, 2026) lets contractors keep installing R-410A systems made before 2025 until that stock runs out, so you may still be offered one. New York State kept the January 1, 2026 cutoff. R-410A production keeps stepping down, so servicing an older system will get more expensive over time.
04
Save money
How to save
Get at least three quotes for the same tonnage and SEER2 rating, and book in spring or fall when contractors have time. Check your utility for rebates on efficient systems; there is no federal tax credit for systems installed in 2026.
If the furnace is more than 15 years old, price both together: $6,500–$16,000 for the pair usually costs less than two separate jobs.
05
Watch out
Permits and red flags
Most cities and counties require a mechanical permit to replace a central AC, usually $100–$250 and normally included in a contractor's quote. A contractor who suggests skipping it is a red flag, as is any quote with no model numbers, no load calculation on a size change, or a price far below $4,000 for a 3-ton system.
06
Worked example
Worked example: a 3-ton AC replacement, line by line
Here is what a full quote for a 3-ton system on good ducts can look like at typical US prices. The base price already covers the outdoor unit, a matched indoor coil, removal of the old unit and startup.
Line itemCost
3-ton central AC, installed (outdoor unit + matched coil + removal + startup)$6,200
New refrigerant line set (if the old one is the wrong size or dirty)$400
New condenser pad (if the old one is cracked or sunk)$120
Smart thermostat, installed (optional)$300
Permit (if it is listed on its own line)$175
Total at typical prices$7,195
Your base price may already include the line set, pad or permit. Ask which of these lines are in the base price so you do not pay twice.
07
Compare
Federal efficiency minimums for a new central AC in 2026
The lowest rating a new split AC can have depends on where you live. A higher rating costs more up front and uses less power.
Region
States
Minimum for a new split AC
What the rule checks
North
All states not listed below
13.4 SEER2
The date the unit was made
Southeast
AL, AR, DE, FL, GA, HI, KY, LA, MD, MS, NC, OK, SC, TN, TX, VA and DC
14.3 SEER2 under 45,000 BTU (under about 3.75 tons); 13.8 SEER2 at 4 tons and up
The date the unit is installed
Southwest
AZ, CA, NV, NM
14.3 SEER2 under 45,000 BTU; 13.8 SEER2 at 4 tons and up, plus an EER2 (hot-day) minimum
The date the unit is installed
Heat pumps (all regions)
Every state
14.3 SEER2 and 7.5 HSPF2
The date the unit was made
In the Southeast and Southwest, a contractor may not install a unit below the regional minimum, even one sitting in a warehouse. Source: U.S. Department of Energy.
08
Compare
Leftover R-410A unit or new-refrigerant unit?
You may be offered either one in 2026. Here is how they differ.
Leftover R-410A system
New A2L system (R-454B or R-32)
Can it be installed in 2026?
Yes, if it was made before January 1, 2025. Not in New York State.
Yes, everywhere
Are new ones still being made?
No. Only parts for repairs are still made.
Yes. This is what makers build now.
Refrigerant supply later
Shrinking. The federal cap on supply drops again in 2029.
Growing
Indoor coil
Must be an R-410A coil matched to the outdoor unit
Must be an A2L-rated coil matched to the outdoor unit
Price to ask about
Ask for a lower price than a new A2L unit of the same size and SEER2
Compare with the prices in the table above
A2L means the refrigerant is rated as mildly flammable. New A2L systems are built and installed to safety rules for that. Many new indoor coils include a small leak sensor.
09
Compare
AC only, AC plus furnace, or a heat pump?
If your furnace is also old, price the other options before you sign. Prices are installed, for a 3-ton home on existing ducts.
Option
Installed price
Makes the most sense when
Replace the AC only
$4,000–$9,000
The furnace is under about 10–12 years old and works well
Replace AC and gas furnace together
$6,500–$16,000
Both are past about 15 years, or the furnace needs a big repair
Heat pump instead of the AC
$5,500–$12,500
Winters are mild, or you want electric heat with the furnace as backup
Quotes only compare well when they price the same job. Do these steps in order.
Get the size from a load calculationAsk each contractor how they picked the size. A Manual J load calculation looks at your walls, windows, insulation and climate. Building codes call for one. Matching the old unit is not enough, because many old units are too big. You can check a rough size with our AC size calculator.
Line up the same tons and SEER2Write down the tons and SEER2 rating from each quote. If one quote is 3 tons at 14.3 SEER2 and another is 3.5 tons at 17 SEER2, they are different jobs.
Check the model numbersEach quote should list the outdoor unit and the indoor coil or air handler by model number. Ask for the AHRI certificate number. It proves the two parts are a rated match.
Ask which refrigerant it usesAsk if the system is R-410A, R-454B or R-32. If it is R-410A, ask when it was made and why the price is not lower.
List what is includedCheck for the line set, pad, electrical disconnect, drain line, thermostat, permit, removal and startup. Mark anything that is extra.
Compare warrantiesWrite down the parts warranty, the labor warranty and any registration deadline. Labor coverage often differs most between companies.
Run the price through a checkPaste the quote into our quote checker to see where it falls against local prices.
11
Watch out
More red flags in an AC replacement quote
Walk away or ask hard questions if you see any of these.
The quote lists the outdoor unit but no indoor coil or air handler model.
The contractor will not give an AHRI certificate number for the matched system.
The size is picked only by square feet or by copying the old unit, on a home that has changed (new windows, insulation or an addition).
An R-410A system is quoted at full price and the quote does not say what refrigerant it uses.
You are told a federal tax credit applies to a 2026 install. That credit ended for work done after December 31, 2025.
You are told R-410A systems are now illegal everywhere, to rush a sale. In most states, units made before 2025 can still be installed. New York is the main exception.
There is no startup check, such as measuring the refrigerant charge and airflow, written into the job.
You are asked to pay the full price before any work is done.
12
Tip
One number that protects you
Ask for the AHRI certificate number before you sign. It is free to look up. It shows the real SEER2 rating of your exact outdoor unit and coil together. If a contractor swaps in a different coil later, the number will not match.
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05 / Questions11 answers
AC replacement cost: FAQ
How much does it cost to replace a 3-ton central AC?
$4,000–$9,000 on existing ducts, installed, with $6,200 typical. Budget more for a high-efficiency unit, an attic or rooftop install, or a new line set.
Should I replace the AC and furnace at the same time?
If the furnace is more than about 15 years old, usually yes. Both together run $6,500–$16,000, and you get one install, one warranty start date and a matched coil.
Can I just replace the outdoor unit?
Rarely. New systems use different refrigerants than older ones, so the indoor coil has to match the new outdoor unit. A condenser-only swap usually voids the matched efficiency rating and can void the warranty.
Is a higher SEER2 rating worth it?
In hot climates, often yes. A 17+ SEER2 unit costs about $2,100 more on a 3-ton system and uses roughly 15–20% less power than a 14.3 SEER2 unit. In the North, where AC runs a short season, the minimum is usually the better buy.
Is there a tax credit for a new AC in 2026?
No federal one. The Energy Efficient Home Improvement Credit (25C) covered improvements made through December 31, 2025 (irs.gov). Check your utility and state for rebates.
Can I still get an R-410A air conditioner in 2026?
Yes, in most states. An EPA rule that took effect July 27, 2026 lets contractors install R-410A systems made before January 1, 2025 until that stock runs out. New York State does not allow it. No new complete R-410A systems are being made.
How much does a 4-ton or 5-ton AC cost to replace?
A 4-ton system runs $4,950–$11,100 installed, about $7,650 typical. A 5-ton system runs $5,600–$12,600, about $8,700 typical. Prices assume your ducts can be reused.
How much does a 2-ton AC cost to replace?
$3,350–$7,500 installed, with $5,200 typical. That size usually suits a smaller home or condo. Have the size checked with a load calculation.
Should I fix my AC compressor or replace the whole system?
A compressor out of warranty costs $1,300–$3,000. A full 3-ton replacement costs $4,000–$9,000. If the system is past about 10–12 years old, the new system is usually the better buy. If it is younger and the compressor is under a parts warranty, a repair often makes sense.
Do I need a permit to replace my AC?
In most US cities and counties, yes. A mechanical permit usually costs $100–$250. The contractor normally pulls it and adds it to the quote. Some places also need an electrical permit.
Is a heat pump cheaper than replacing my AC?
Not up front. A 3-ton heat pump runs $5,500–$12,500, against $4,000–$9,000 for an AC. A heat pump also heats your home, so it can cut furnace use. The federal tax credit for heat pumps ended for work done after December 31, 2025.
These are independent estimates built from national cost guides, local reported-job averages, manufacturer and utility pages and EIA energy prices. No contractor can pay to change them, so always get a couple of quotes. Last reviewed November 2026. Read the full methodology →