How Much Does It Cost to Replace AC and Furnace Together?

Replacing an AC and furnace at the same time is one of the smartest moves a homeowner can make — if the timing is right. But what does it actually cost, and how do you know whether a combined replacement is the right call? This guide covers the real costs, when it makes sense, and the alternatives worth considering.

What does it cost to replace both?

A combined AC and furnace replacement costs more than either job alone, but typically less than doing them as two separate projects, because the contractor shares the labor, permits, ductwork assessment, and thermostat wiring across both. The exact figure depends on your AC tonnage, furnace efficiency, state labor rates, and ductwork condition. Estimate yours with the AC + furnace cost calculator.

Signs it is time to replace both

If both units are over 12 years old, your energy bills have been climbing for several years, the existing AC uses an older refrigerant that is being phased out, or one unit has already failed and the other is aging, replacing both together is usually the best value. Matching new units ensures the system is properly paired for peak efficiency — a new high-SEER2 condenser paired with an old air handler delivers less savings than a matched pair.

When to replace only one

If one unit is relatively new (under 7 to 8 years old), the surviving unit is in good condition, and the failed unit can be replaced with a compatible match, doing just the one replacement is the more cost-effective move. Ask the contractor to verify that the new and existing units are compatible on refrigerant type, airflow capacity, and control wiring.

The heat pump alternative

Instead of replacing both an AC and a furnace, you can replace them with a single heat pump that handles both cooling and heating. The installed cost is often comparable, and the running cost is lower in mild to moderate climates. Compare: heat pump cost vs AC + furnace cost, and running cost via the heat pump vs furnace calculator.

How to save on a combined job

Get at least three bids for the combined project. Schedule in spring or fall when contractors are less busy. Ask about utility rebates for both units — some programs offer separate rebates that stack. And confirm that the contractor is doing a Manual J load calculation to ensure both units are correctly sized for your home, not just matching whatever was there before.

Frequently asked questions

How much does it cost to replace an AC and furnace?

A combined replacement costs more than either unit alone but less than two separate projects. Use the AC + furnace cost calculator for your state-specific range.

Should I replace AC and furnace at the same time?

If both are over 12 years old or one has failed and the other is aging, replacing both saves on labor and ensures a matched system.

Can I replace my AC and furnace with a heat pump?

Yes. A single heat pump handles both heating and cooling. It often costs about the same installed and runs cheaper in mild to moderate climates.