Open 24/7 for emergencies
AC replacement in Fairfax runs $5,942 to $14,450 installed, inside the city line or out in Fair Lakes, with your gas furnace left in place.
Price range
$5,942-$14,450
8yrs @ 7.99%
$84/mo
15yrs @ 9.99%
$64/mo
Monthly figures on the starting price, the whole price financed, on approved credit. The lender sets the final terms. How financing works
Get your price in writing
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5.0 stars across 1,131 reviews
One of our HVAC technicians moving a new condenser up a driveway, the van behind him.
Licensed and insuredVirginia Class A contractor #2705192276
24/7 emergency serviceOften same-day, and we will tell you honestly when we can get there.
Our own HVAC installersA dedicated heating and cooling team, separate from our plumbers
Price in writing firstYou see every option priced before anything is ordered
What it costs
The same price book our estimator runs on, for a central air conditioner on its own, keeping the furnace you have. A single-stage unit on a small house sits near the bottom; a variable-speed one on a big house, near the top.
A central air conditioner alone, keeping your furnace, installed
$5,942 to $14,450
or $99/mo at 0% APR for 60 months
An air conditioner and furnace together, installed
$8,898 to $23,000
or $148/mo at 0% APR for 60 months
A heat pump in the AC’s place, installed
$8,499 to $21,650
or $142/mo at 0% APR for 60 months
Diagnostic visit, if it may be worth fixing
$99
Monthly figures: 60mo @ 0% APR on each starting price, the whole price financed, on approved credit. Longer plans lower the payment and cost more in total. The lender sets the final terms. How financing works
The HVAC replacement cost estimator narrows it to your house. Then a tech measures, and you get the installed price in writing before anything is ordered.
With Comfort+ membership at $199 a year, the diagnostic visit is included, and half of each repair bill is banked toward replacing that system, up to $1,500.
What’s different in Fairfax
Inside the City of Fairfax the typical owner’s house went up in 1966, about two thirds before 1980, and close to seven in ten owners heat with gas. Many of those houses got central air after they were built, so the coil sits on a gas furnace and the cold air rides ducts first laid out for heat alone, often with a small return. That shapes the replacement. A bigger condenser on those ducts gets louder without cooling better, so the tech measures the return and the static pressure and sizes the new AC for what the ducts can carry.
The city line also decides the paperwork. The City of Fairfax runs its own permit office, and a Fairfax mailing address outside the line goes through Fairfax County instead, which counts a cooling replacement as mechanical permit work and wants an A2L system certification with it, since new air conditioners run on those refrigerants. Two houses with the same Fairfax mail can answer to different inspectors. Before anyone quotes, ask which office your street is under: the permit, its timing and the person who checks the work all follow it.
Past the line the houses get younger. On the county side the homes split about evenly between before 1980, the 1980s and 90s, and since 2000. Fair Lakes and Navy went up mostly in the late 1990s and 2000s, and in Fair Lakes about a third of the homes are townhouses, with condensers in a row out back a few feet apart. Some are still the builder’s, past twenty-five summers and most likely on R-22. A new one has to fit the same slot and keep its clearance from the neighbor’s, and a newer unit can be taller or wider.
Fair Oaks and Merrifield are condo country, about half of Fair Oaks’ homes and most of Merrifield’s, and across the county side about three in ten homes are in condo and apartment buildings. There the outdoor unit sits on a roof, a balcony or a shared pad, and the association usually approves the new one before it goes in. Kings Park West runs the other way: close to half its homeowners heat with electricity, mostly with heat pumps, and those houses replace a heat pump system at $8,499 to $21,650, not an AC alone.
Neighborhood by neighborhood
Census figures for the owner-occupied homes in each place, and what that usually means for the AC that’s there now.
| Place | Median home built | Most homes are | Heated with | The AC there now |
|---|---|---|---|---|
| Fair Oaks | 1995 | condo and apartment buildings, about 5 in 10 | gas, about 6 in 10 | Condo and apartment buildings: compact condensers on shared pads and roofs. |
| City of Fairfax | 1966 | single-family houses, about 5 in 10 | gas, about 7 in 10 | Gas furnaces with central air, often on the second or third AC. |
| Fairfax Station | 1982 | single-family houses, about 9 in 10 | gas, about 5 in 10 | 1980s and 90s houses, many on their second air conditioner. |
| Kings Park West | 1976 | single-family houses, about 7 in 10 | gas, about 5 in 10 | Gas furnaces with central air, often on the second or third AC. |
| Merrifield | 1990 | condo and apartment buildings, about 6 in 10 | gas, about 6 in 10 | Condo and apartment buildings: compact condensers on shared pads and roofs. |
| Fair Lakes | 1998 | townhouses, about 3 in 10 | gas, about 7 in 10 | 1980s and 90s houses, many on their second air conditioner. |
| Long Branch | 1968 | single-family houses, about 9 in 10 | gas, about 7 in 10 | Gas furnaces with central air, often on the second or third AC. |
| Mantua | 1968 | single-family houses, about 7 in 10 | gas, about 7 in 10 | Gas furnaces with central air, often on the second or third AC. |
By the numbers
From the Census Bureau’s 2020 to 2024 survey, owner-occupied homes unless it says otherwise.
Most of the Fairfax Station Census place, in the table, has Fairfax mail, so it counts here.
When it’s time
In a City house that got central air later, a condenser fighting a small return can run for hours without bringing the rooms down, and an older one on R-22 loses ground every summer as it leaks. Before buying a bigger unit, have the airflow measured. If the ducts are the limit, the right replacement is sized to them, with a return added if the house needs one.
An air conditioner put in before 2010 most likely holds R-22, which hasn’t been made since 2020. A leak on one of those usually ends the repair road.
The new coil sits on the furnace and uses its blower. When the furnace is the same age, replacing both usually costs less than two jobs a few years apart: $8,898 to $23,000 for the pair.
Permits, locally
Our Virginia Class A contractor license, 2705192276, is on the side of the van.
Choosing who installs it
Questions to ask anybody who quotes you, us included.
In a 1960s City of Fairfax house, one small return in a hallway often limits how much air the whole system moves. Ask the installer to measure it, and to say in writing whether the quote adds return capacity or sizes the new AC to what’s there. Either can be right; skipping the question isn’t.
Ask how they picked the size. Copying the old nameplate repeats whatever was guessed when the house was built.
The outdoor unit and the coil on the furnace are rated as a pair. Ask whether the quote replaces both, and what happens to the line set.
A good company puts the repair price next to the replacement range and lets you choose. Already holding somebody’s big number? Take the free second opinion first.
Two of our crew going over a work order before the day's calls.
From our Google reviews
5.0 stars across 1,131 reviews. Read them on our reviews page.
I would gladly recommend them to anyone in the greater Fairfax/Alexandria area without reservation.
Swiftpro came out the same day I called when my AC was out and had it fixed in less than an hour after arriving.
On spec and on price for our A/C replacement. Showed up on time and all went as promised
Questions
A Fair Lakes builder unit from the late 1990s has outlived most central air conditioners, and one that old was most likely charged with R-22 at the factory. If the fix is a capacitor or a contactor, buying another summer can make sense. If it’s the compressor or a refrigerant leak, it rarely does. The $99 diagnostic puts a repair price in your hand to weigh against this range.
The association. Your condo documents say whether the outdoor unit is yours or the building’s and what a replacement has to look like, and the management office usually sets how the new one gets up there. Once that’s settled, we replace the condenser and the coil on your air handler or furnace together, matched for the new refrigerant.
$5,942 to $14,450 installed for a central air conditioner on its own, keeping the furnace you have; size and efficiency set where yours lands. An AC and furnace together run $8,898 to $23,000. The HVAC replacement cost estimator gives your house its own number.
It’s worth pricing. A heat pump cools exactly like an AC and also heats on mild days, so with your gas furnace it becomes dual fuel. A heat pump system runs $8,499 to $21,650 installed, and we’ll price it both ways.
Ready when you are
Call, or send the form at the top. A tech measures the house and puts the installed price in writing before anything is ordered, and if the old AC is worth fixing, you’ll hear that first.
SwiftPro Heating, Cooling & Plumbing
4230 Lafayette Center Dr N, Chantilly, VA 20151
44679 Endicott Dr, Suite 211, Ashburn, VA 20147
Virginia Class A contractor license #2705192276
SwiftPro Heating, Cooling & Plumbing is a licensed, BBB Accredited (A rating), independently owned heating, cooling and plumbing company in Chantilly, serving Fairfax and the rest of Northern Virginia. Virginia contractor license #2705192276. 5.0 stars across 1,131 reviews on Google, Angi, Yelp, the BBB and Facebook. SwiftPro maintains a dedicated HVAC team and a dedicated plumbing team.
From SwiftPro Heating, Cooling & Plumbing in Chantilly. Housing figures are the Census Bureau’s American Community Survey, 2020 to 2024, for each place named; permit, water and sewer facts link to each office’s own page and were checked in September and October 2026.