Home Fix Cost Guide
HVAC

Cost to Replace a Central AC Unit

By Diana Reyes 9 min read

The cost to replace a central AC unit is $3,800 to $9,500 for a typical home, installed. A small, low-efficiency system swap sits near the bottom. A large, high-SEER2 system with a new coil, line set, and electrical work sits near the top.

This guide breaks the job into the equipment, the labor, and the parts that do not always get replaced. It also covers sizing, efficiency ratings, and where the price is negotiable.

What It Costs to Replace a Central AC Unit

Most homeowners pay $5,000 to $8,000 to replace a central AC unit matched to the existing furnace. The outdoor condenser and the indoor coil are the bulk of that. Labor is $1,200 to $2,500 for one to two days.

A cheaper job is possible when the ductwork, the line set, and the electrical are all in good shape and you stay at a standard efficiency. A pricier job adds a new coil, a new line set, a pad, a disconnect, and a permit.

The table below shows installed cost by system size. Read the sizing section before you accept any quote, because an oversized unit is a common and costly mistake.

AC Size and What It Means

Cooling capacity is measured in tons. One ton removes 12,000 BTU of heat per hour. A tight 1,200-square-foot home might need 2 tons; a 2,400-square-foot home in a hot climate might need 4.

Bigger is not better. An oversized AC cools the air fast but shuts off before it removes humidity, so the house feels clammy and the unit wears out from short cycling.

A contractor sizes it with a Manual J load calculation, not a rule of thumb off the square footage. Ask for it in writing. If a bidder sizes by eyeballing the old unit, keep shopping.

SEER2 and Efficiency

Efficiency is rated in SEER2. The legal minimum is 13.4 to 14.3 depending on your region. Higher-SEER2 units cost more up front and use less electricity every summer.

A jump from 14 to 17 SEER2 adds roughly $1,000 to $2,500 to the equipment. Whether it pays back depends on your electricity rate, your cooling season, and how long you will own the home.

For a mild climate or a short stay, the base efficiency is fine. For a long hot season and a long stay, mid-tier efficiency usually wins. Two-stage and variable-speed units cost more and mainly buy comfort and quiet.

Where the Money Goes

The outdoor condenser is $1,500 to $4,000. The matched indoor coil is $600 to $1,500. Together they are more than half the job.

Labor is $1,200 to $2,500. A refrigerant line set, if it has to be replaced, is $300 to $800. A new pad, a whip and disconnect, and a condensate line add $200 to $600.

A permit and inspection are $75 to $500. See our HVAC cost guides for how the furnace and duct work is priced.

What Drives the Price Up

A coil and blower that no longer match the new condenser force a full indoor swap, which is the difference between a $5,000 and an $8,000 job. A switch to a different refrigerant does the same.

A rooftop or attic air handler, a crawlspace with no room to work, or a long line set run all add labor. Undersized ductwork that has to be reworked can add $1,000 to $4,000.

Adding AC to a house that only has a furnace, rather than replacing an existing system, is a bigger project. Our cost to install a heat pump guide covers the all-in-one alternative.

Replace the AC Only, or the Whole System?

If your furnace is under about 10 years old and healthy, replacing just the AC and the coil is reasonable. Keep the paperwork so the warranty on the new parts stays valid.

If the furnace is also aging, replacing both at once saves a second mobilization and a second permit, and it guarantees the blower and coil are matched. A matched system also runs more efficiently.

A heat pump is worth pricing here too. It replaces the AC and does most of the heating, and our cost to install a gas furnace guide compares the heating side.

Signs Your AC Needs Replacing

Age is the headline. A central AC lasts 12 to 17 years. Past 12, a major repair such as a compressor or a coil is usually money spent on a unit near the end.

Rising electric bills with no change in habits, weak airflow, warm air, or a unit that runs constantly on a mild day all point to a failing system. Frequent refrigerant top-offs mean a leak that is only getting worse.

If your system still uses R-22 refrigerant, which is no longer produced, any significant repair tips the math toward replacement.

Permits, Timing, and Rebates

AC replacement needs a permit and an inspection in most areas. The contractor pulls it, and the inspector checks the electrical, the refrigerant handling, and the condensate drain.

Spring and fall are the low season. Quotes are lower and scheduling is faster than in a July heat wave, when every contractor is booked and emergency rates apply.

Rebates are common for higher-efficiency equipment. Check the Department of Energy central air page and your utility before you buy.

Regional Cost Differences

Labor rate is the biggest reason two quotes differ. A licensed HVAC contractor in a coastal metro bills far more per hour than one in a rural area, and labor is a large share of the job.

Climate drives the equipment choice, and that changes the price. A hot, humid region needs more cooling capacity and benefits from variable-speed equipment, both of which cost more than a basic unit in a mild climate.

Local code adds too. Some areas require a hard-start kit, a surge protector, or a specific condensate safety switch on every install. A good local contractor prices these in; an out-of-area bid may not.

What to Expect on Install Day

A same-size swap is a one-day job. The crew recovers the old refrigerant, removes the condenser and coil, sets the new equipment, brazes the connections, pulls a vacuum on the lines, and charges the system.

They then test the airflow, the temperature split across the coil, and the safety switches, and walk you through the new thermostat. The city inspection usually happens a few days later.

Plan for the house to be warm for part of the day while the system is down. If it is a heat wave, ask whether they can start early to limit that window.

How to Keep the Cost Down

First, get three itemized quotes that each include the load calculation, the equipment model numbers, and the SEER2 rating. Compare like for like.

Second, replace in the shoulder season. Third, keep the existing line set and pad if the contractor confirms they are sound. Fourth, choose mid-tier efficiency unless your climate and ownership timeline clearly favor the top tier.

Fifth, ask which add-ons are code-required versus recommended, and defer the optional ones.

Bottom Line

Budget $5,000 to $8,000 to replace a central AC unit matched to a healthy furnace, and $8,000 to $12,000 for a full system with high efficiency and duct work. A simple like-for-like swap can come in under $5,000.

Insist on a Manual J load calculation, replace in the shoulder season, and pick efficiency to match your climate. If the furnace is also old, price the whole system and a heat pump, and keep the ductwork in good shape so the new unit performs.

A few smaller, related jobs come up often alongside this one: furnace igniter, AC capacitor, furnace blower motor. Each has its own detailed cost breakdown if you are budgeting for more than one repair at a time.

Central AC Replacement Cost by Size (Installed) — Condenser and matched coil, standard efficiency, with an existing healthy furnace.
Item Low High Unit
2 tons (up to ~1,200 sq ft) $3,800 $6,500 total
2.5 to 3 tons $4,500 $7,800 total
3.5 to 4 tons $5,500 $9,500 total
5 tons $6,500 $11,000 total
Add for high efficiency (16+ SEER2) $1,000 $2,500 total
AC Replacement Cost Breakdown — Typical 3-ton like-for-like job.
Item Low High Unit
Outdoor condenser $1,500 $4,000 total
Indoor coil $600 $1,500 total
Labor $1,200 $2,500 total
Line set, pad, disconnect, drain $300 $900 total
Permit and inspection $75 $500 total

Frequently asked questions

How long does it take to replace a central AC unit?
One day for a straightforward condenser-and-coil swap. Two days if the air handler, line set, or ductwork also changes, or if the unit is in a tight attic. Add a wait for the inspection.
What size central AC do I need?
It depends on climate, insulation, windows, and layout, not just square footage. A contractor runs a Manual J load calculation. As a rough guide, homes need about one ton of cooling per 500 to 700 square feet in a hot climate.
Is it worth paying for a high-SEER2 AC?
In a long, hot cooling season with high electricity rates and a plan to stay in the home, yes. In a mild climate or a short stay, the base efficiency usually makes more financial sense.
Can I replace just the outdoor AC unit?
Sometimes, but only if the indoor coil matches the new condenser and uses the same refrigerant. A mismatched pair runs poorly, voids the warranty, and often fails early, so contractors usually replace both.
Do I need a permit to replace a central AC unit?
Yes, in most jurisdictions. The contractor pulls it and the city inspects the electrical, the refrigerant work, and the condensate drain. An unpermitted install can complicate a home sale or an insurance claim.