Replacing the AC when the furnace is new: condenser, coil, or heat pump

The outdoor unit failed in July and the furnace is four years old, so the person in the driveway says they can “just replace the AC.” That sentence hides three different machines. One is a new condenser sitting on the old indoor coil. One is a matched outdoor unit plus a new coil on top of the furnace you keep. One is a heat pump that cools in summer and heats until the furnace takes over. Those prices are not in the same neighborhood, and mixing the refrigerant, the blower, or the rating number is how you buy a summer that still does not cool.

If you already know you want the furnace to stay as backup heat, dual fuel is the control conversation: written outdoor cutoff, capacity at your January, not a factory 40°F lockout. Stay here when the live question is whether AC-only is honest at all.

What do the three jobs actually cost?

Angi’s 2026 AC replacement guide puts a typical professional replacement at $5,978, with a wide published range of $1,400 to $12,500. Their central-air line is $2,500 to $4,500 for the equipment plus $3,500 to $7,000 for installation, and they flag $3,887 to $8,073 as the labor band depending on system type. Ductwork changes, if anyone opens the attic, add $3,000 to $7,500.

Angi: AC replacement cost

HomeGuide’s 2026 AC replacement page is tighter on the equipment you are actually buying. A standard-efficiency changeout lands $5,000 to $8,300 installed. Mid-range two-stage work is $8,300 to $12,500. Variable-speed, high-SEER2 systems run $12,500 to $14,000+. A 3-ton outdoor unit in their size table is $5,800 to $7,800 installed.

HomeGuide: AC replacement cost

That is the matched job: new outdoor, new indoor coil, new refrigerant, permit. It is not the condenser-only number.

HomeGuide prices a full condenser swap at $1,200 to $4,200 ($2,900 as the average they publish), or $300 to $1,200 labor if the part is still under warranty. The part alone is $850 to $3,000. A 3-ton condenser in that table is $1,400 to $3,100 installed.

HomeGuide: AC condenser replacement

The indoor coil that sits on your furnace is its own line. HomeGuide’s evaporator-coil page is $1,000 to $2,500 when the unit is still under warranty and $2,500 to $4,500+ when it is not, parts, labor, and refrigerant included. A 3-ton coil is $1,800 to $3,000.

HomeGuide: evaporator coil replacement

Add those two HomeGuide bands and you are back near Angi’s replacement average, which is the point. A $2,900 condenser on a ten-year-old coil is not the $6,000 matched system. If the quote is the low number, ask which indoor coil they are keeping.

The third job is dual fuel. EnergySage’s 2026 marketplace average for a hybrid (heat pump plus furnace) is $14,353 before incentives, next to $14,529 for a ducted heat pump and $15,393 across every type they see. After the state and utility programs in their table, hybrids drop to $10,695. That “after” column is local money, not a federal credit.

EnergySage: heat pump cost

A keep-the-furnace heat pump should come in under that hybrid average because you are not buying a second indoor cabinet. If the dual-fuel bid is $6,000 over the matched AC bid, find the furnace. If it is only a few hundred over, you are looking at an outdoor unit that heats, and that is often the whole argument.

The IRS Energy Efficient Home Improvement Credit (25C) covered qualifying heat pumps placed in service through December 31, 2025, at 30% with a $2,000 annual cap. Central air conditioners were never on that heat-pump line. If the unit starts running in 2026, do not let last year’s brochure knock $2,000 off either bid.

IRS: Energy Efficient Home Improvement Credit

Why can’t they just swap the box outside?

Because the rating on the sticker is for a pair, not a condenser. AHRI (the Air-Conditioning, Heating, and Refrigeration Institute) certifies outdoor-plus-indoor combinations. ENERGY STAR’s own field list for heat pumps and air conditioners carries an AHRI reference number and, for coil-only machines, a furnace model the combination was tested with. The SEER2 number on the brochure is that pair. Bolt a new 16 SEER2 outdoor unit onto the coil that came with the 2018 furnace and you do not own a 16 SEER2 system. You own an unmatched pair whose capacity, humidity removal, and warranty the manufacturer may not stand behind.

ENERGY STAR: air-source heat pump certified products

Ask for the AHRI certificate number on the quote, the outdoor model, and the indoor coil model. If they cannot produce the combination, they are selling you an outdoor unit with no match. That is a real product category in DOE rules, and it is tested as a worse case on purpose so manufacturers cannot advertise the pretty number from a coil they are not installing.

The furnace blower still has to move the air the new coil wants. A 2.5-ton coil on a furnace that was set up for 2 tons will freeze the coil or leave the back bedrooms hot. A 4-ton outdoor on a 3-ton coil short-cycles and does not wring humidity. The written heating and cooling load for this house (Manual J) is how you know the tonnage, not the square-footage rule on the side of the van.

If the indoor coil is leaking, or if it is the same refrigerant circuit as the dead compressor, replacing only the outdoor unit leaves the leak in the attic. HomeGuide’s compressor line is $1,300 to $2,500. That repair on a matched 12-year-old pair is often how you get talked into “just the condenser” when the coil is already stained.

What did the refrigerant change do to this bid?

New residential split-system air conditioners and heat pumps that use refrigerants above a global warming potential of 700 (R-410A is in that bucket) faced a January 1, 2025 manufacture and import cutoff under EPA’s AIM Act Technology Transitions program. New systems use lower-GWP A2L refrigerants, mostly R-454B or R-32. EPA’s sector table still lists that GWP 700 limit for residential and light-commercial unitary systems, and it also says there is no installation compliance date when every specified component was manufactured or imported before January 1, 2025. Pre-2025 R-410A inventory can still go in until it is gone. Existing systems can be serviced for the rest of their life. Components labeled for repair of legacy equipment are not the same as a new matched system.

EPA: Technology Transitions HFC restrictions by sector

EPA: Technology Transitions Program

You cannot mix those families on one circuit. An R-454B outdoor unit does not run on the R-410A coil that came with the furnace. Oil, valves, and sensors are different, and the leak behavior is different (A2L is mildly flammable, which is why the installer talks about charge limits and sensors). If the furnace coil is R-410A and the only outdoor units on the truck are R-454B, “AC-only” means a new coil anyway. That is not an upsell. That is physics.

A leftover R-410A condenser from 2024 stock can still be a legal match to your existing coil if the AHRI combination exists and the coil is healthy. Ask for the manufacture date on the data plate, not a promise that “410A is fine forever.” Supply shrinks. Recharge prices move. The honest bid names the refrigerant on both ends.

Servicing the system you already have is still legal. If the compressor is the only failure, the furnace is young, and the coil holds, a warranty condenser or an OEM R-410A replacement coil-plus-condenser can be the smaller check. If anyone is quoting a home warranty to cover that swap, read what the contract excludes before you file. Mismatched coil and condenser is a classic denial.

When is AC-only the honest bid?

It is honest when all of this is true at once.

The furnace is actually young and the heat exchanger is fine. Four to eight years is the window this page is for. Twelve years with a cracked exchanger is two replacements pretending to be one. Ask them to inspect the heat exchanger and write the furnace serial date on the quote.

The indoor coil can be matched. Same refrigerant family, AHRI combination, blower speed that hits the coil’s required CFM. If they have to change the furnace cabinet to take the new coil, you are not in AC-only anymore.

You are not trying to heat with the outdoor unit. Summers-only cooling, cheap winter gas, and a furnace you already paid for is the case for a straight AC. If January is brutal and electricity is cheaper than gas, or if you were going to look at a heat pump in three years anyway, paying twice for the outdoor pad is the expensive path. Heat pump vs furnace is that climate math. Operating cost vs gas is the bill.

You do not need the 25C heat-pump credit, because it is gone for 2026 installs anyway. State and utility rebates may still pay for a heat pump and not for an AC. Ask whether the rebate needs the equipment running this year, and whether AC-only even qualifies.

When should the outdoor unit be a heat pump instead?

When the extra money is mostly the outdoor chassis and the coil you were replacing anyway. EnergySage’s hybrid average sits near their ducted heat-pump average, which is how you know a lot of “keep the furnace” jobs are priced like a heat pump, not like an AC plus a surprise furnace.

It also makes sense when you want one outdoor pad to cover shoulder-season heat so the furnace sleeps until the real cold. Dual fuel is that plan, and it only works if the switchover temperature is on paper. Reading SEER2, HSPF2, and EER2 keeps the cooling sticker from hiding a machine with no heating capacity at 5°F. The quote checklist is the line-by-line version.

A mild-climate 14.3 SEER2 heat pump that gives up at 40°F is an AC with extra valves. If that is the dual-fuel bid, buy the matched AC and keep the furnace as the heater it already is.

If the panel is 100 amps and the outdoor unit is a heat pump with electric strips, the electrical conversation is the 200-amp upgrade, not a footnote. Straight AC on an existing 240-volt disconnect usually stays on the circuit you have.

What should three real-looking bids mean?

Bid A, condenser only. New outdoor, old coil, same refrigerant, no AHRI match, cheapest number. Accept this only if the coil is young, holds pressure, and the manufacturer will warrant the combination. Otherwise it is how you pay for a second outdoor unit in two summers.

Bid B, matched AC on the existing furnace. New outdoor, new cased coil, new TXV or electronic expansion valve, new lineset or a flush they will stand behind, permit, startup charge weighed in. This is Angi’s $5,978 neighborhood and HomeGuide’s $5,000 to $8,300 standard band. The furnace stays. The data plates should be the same refrigerant.

Bid C, dual-fuel heat pump, keep the furnace. Outdoor heat pump, matched coil, dual-fuel thermostat, written switchover, permit. Price it against EnergySage’s $14,353 hybrid average and against Bid B. The gap is what you pay to heat in April and October without burning gas.

If Bid B and Bid C are within a few thousand after rebates, and your winter is real, Bid C is usually the one you keep for a decade. If Bid C is Bid B plus a new 96% furnace you did not ask for, they sold you Bid B from the dual-fuel page.

Get the load calculation, the AHRI number, the refrigerant, the furnace age, and whether the coil is included, in writing, on all three. Compare those five lines, not the monthly payment.

What has to be on the quote?

Outdoor model, indoor coil model, AHRI reference, SEER2 for that pair (and HSPF2 if it is a heat pump).

Refrigerant by name on both ends, and whether the lineset is reused, flushed, or replaced.

Furnace brand, model, serial, age, blower CFM they will set, and a heat-exchanger note.

Tonnage from a written load, not from “this house is 2,000 square feet.”

Permit, startup, weighed-in charge, and who owns the first-year leak.

Thermostat: a dual-fuel job needs an outdoor sensor and a lockout you can read. A cooling-only job can keep the thermostat you have if it already talks to the furnace.

If they will not put the coil on the page, they are bidding Bid A at Bid B money.

How does this go wrong?

The condenser is new, the coil is old, the house is loud, and August humidity never drops.

The new R-454B outdoor is piped to an R-410A coil because “they both cool.”

The furnace is “new” in the sales story and 14 years old on the door sticker.

A 2026 bid still subtracts a $2,000 federal credit that ended on December 31, 2025.

The matched AC is sized from square footage, so the coil ices and the filter pulls wet. Filter size and MERV is the cheap check after the install. Heat pump maintenance is the same outdoor-coil cleaning habit if you went dual fuel.

How do I decide this week?

1. Photograph the furnace data plate, the outdoor data plate, and the indoor coil if you can see it, and write the refrigerant and the years on one card.
2. Ask whether the coil holds. If it does not, condenser-only is already dead.
3. Get Bid A, Bid B, and Bid C with AHRI numbers, not a single “replace the AC” price.
4. Check whether any 2026 rebate applies to a heat pump and not to an AC, and ignore federal 25C on both.
5. If Bid B is the matched coil and the furnace is truly young, that is the AC-only job this page is for.
6. If Bid C is close to Bid B and you have a real winter, take the dual-fuel conversation to that quote and write the cutoff down before anyone orders the box.