Air conditioner replacement cost
Replacing a central air conditioner costs $4,800 to $9,500 for the most common size, typically around $6,800 for a 3 ton system on existing ductwork.
National average
$6,800
per project
On this page
- Cost by system size
- Why the same house gets quotes $3,000 apart
- The line items that turn up
- Repair or replace
- Getting the sizing right
- Frequently asked questions
- Can I replace just the outdoor unit?
- What is SEER2 and does it matter?
- How long does the installation take?
- Is it cheaper to replace in winter?
- My contractor says I need a bigger unit than I have. Should I believe them?
Replacing a central air conditioner costs $4,800 to $9,500 for the most common size, with a typical 3 ton job landing near $6,800. That buys a new outdoor condenser, a matched indoor coil, refrigerant line work, a permit and start-up on ductwork you already have.
Size drives the price more than anything else, and size is measured in tons. One ton is 12,000 BTU per hour of cooling capacity. It has nothing to do with weight.
Cost by system size
| Capacity | Suits roughly | Low | Typical | High |
|---|---|---|---|---|
| 2 ton | 900 to 1,200 sq ft | $3,800 | $5,400 | $7,000 |
| 3 ton | 1,500 to 1,900 sq ft | $4,800 | $6,800 | $9,500 |
| 4 ton | 2,000 to 2,600 sq ft | $5,600 | $8,200 | $12,000 |
| 5 ton | 2,600 to 3,300 sq ft | $6,500 | $9,500 | $14,000 |
Above 5 tons a house normally gets two systems rather than one larger one, which is a different and more expensive conversation.
The square footage column is a starting point, not an answer. A well-insulated house with modern windows in Oregon needs far less capacity per square foot than a 1960s house with single glazing in Texas.
Why the same house gets quotes $3,000 apart
Efficiency tier. SEER2 is the cooling efficiency rating. A baseline system today is around 14 SEER2. Going to 16 adds roughly $800 to $1,500; going to 18 or above adds $2,000 to $4,000 and usually brings a variable-speed compressor with it. Whether that pays back depends on how many hours a year you actually run the thing. In Phoenix it can. In Seattle it will not.
Single stage against variable speed. A single stage compressor is on or off. A two stage or variable speed compressor runs at part load most of the time, which holds temperature and humidity steadier and is noticeably quieter. It is the upgrade homeowners are most often glad they paid for, and the one least visible on a spec sheet.
Brand. The spread between a value brand and a premium brand on comparable equipment is roughly 15% to 25%. Most residential equipment is made by a handful of parent companies, so the meaningful differences are warranty terms, parts availability and who in your town can service it.
What the old system left behind. A failed compressor that ran acid through the lines means the line set needs flushing or replacing. An R-22 system being replaced needs the lines cleared of mineral oil before modern refrigerant goes in. Neither is optional and neither shows up until someone looks.
The line items that turn up
- Replacing the line set: $600 to $1,500
- New concrete or composite pad for the condenser: $150 to $400
- Electrical disconnect and whip: $150 to $400
- New thermostat, standard: $150 to $300; smart: $250 to $600
- Permit and inspection: $150 to $500
- Electrical panel upgrade where the service cannot carry the unit: $1,800 to $5,500
Repair or replace
An air conditioner is a 15 to 20 year machine. The rough test is to compare the repair against the replacement over the years you would buy.
A $600 capacitor and contactor repair on a 9 year old system is clearly worth doing. A $2,200 compressor on a 16 year old system usually is not: you are spending a third of a replacement on the oldest part of a machine whose other parts are the same age.
Two situations make replacement the clear answer regardless of the arithmetic. If the system uses R-22, any refrigerant leak is a money pit, because the refrigerant is out of production and priced accordingly. And if the evaporator coil has failed on a system out of warranty, the part and the labour together are close enough to a new indoor unit that replacing is better value.
Getting the sizing right
Ask whether the contractor performed a Manual J load calculation. It is the industry-standard method for working out how much capacity a house actually needs, and it accounts for insulation, orientation, window area, air leakage and local design temperature.
Most replacement quotes skip it and simply match the tonnage of what was there. That perpetuates whatever mistake was made the first time, and systems installed in the 1990s were frequently oversized by a full ton. An oversized air conditioner cools the air fast, shuts off before it has pulled moisture out, and leaves a house that is cold and damp at the same time.
Frequently asked questions
Can I replace just the outdoor unit?
Sometimes, but usually you should not. The outdoor condenser and the indoor coil are rated as a matched pair. A new condenser on an old coil will not reach its rated efficiency, and most manufacturers void the warranty on a mismatched installation. It is worth doing only when the indoor coil is recent and the manufacturer lists the combination.
What is SEER2 and does it matter?
SEER2 is the seasonal cooling efficiency rating under the test procedure that took effect in 2023. Higher is better. It matters in proportion to your cooling hours: worth paying for in the south and southwest, marginal in the northern half of the country.
How long does the installation take?
A straight changeout is a one day job. Add a day if ductwork is modified, the electrical service is touched, or the equipment has to be craned onto a roof.
Is it cheaper to replace in winter?
Yes, modestly. HVAC contractors are least busy in the shoulder seasons and most will discount to keep crews working. The saving is usually 5% to 10%, and the bigger benefit is that you are choosing rather than deciding in an emergency in August.
My contractor says I need a bigger unit than I have. Should I believe them?
Only if they measured. If the recommendation follows a load calculation and they can explain what changed, such as an addition or new windows, it is credible. If it is a rule of thumb about square footage, ask for the calculation before you agree to pay for capacity you may not need.
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