AC replacement cost: prices and what drives them

Capacity is measured in tons. The table shows the averages and ranges This Old House publishes for each size. The ranges are wide because they span basic and premium equipment.

Do not pick a size from a table. An oversized AC short-cycles and leaves the house humid, and an undersized one runs constantly. Use the AC size calculator for a rough idea, then ask the contractor for a proper load calculation.

SEER2 measures cooling efficiency. A higher rating costs more to buy and less to run. This Old House states the minimums as 13.4 SEER2 in northern states and 14.3 SEER2 in Southeastern and Southwestern states, so the lowest-efficiency unit a contractor will usually quote depends on where you live.

Paying for a rating well above the minimum makes the most sense where the AC runs for many months of the year. In a mild climate the extra cost can take a very long time to come back through lower bills. Ask each contractor to price two efficiency levels so you can see the real step in cost.

No reliable published table of AC replacement prices by state was found for this page, so none is shown. The reasons prices differ are well understood:

• Local labor rates and licensing costs.
• Permit fees and inspection rules.
• The regional SEER2 minimum.
• Climate, which decides how large and how efficient a unit you need.
• Seasonal demand. Contractors are busiest in the first heat wave.

Check your utility's website for current offers before you sign.

This Old House gives a 50 percent rule: if a repair costs more than half of what a new unit is worth, replacement is usually the better use of the money. Age matters as well. A system close to the end of its expected life is a poor candidate for an expensive repair.

The guide on whether to repair or replace your air conditioner walks through that decision. If your home has no ducts yet, read about central air installation cost instead, because the job and the price are different.

Get at least three written quotes for the same tonnage and SEER2 rating. Each should list:

• The exact model numbers and capacity of the equipment or part being installed.
• Labor, materials and refrigerant listed as separate lines.
• Permit and inspection fees, and who pulls the permit.
• Removal and disposal of the old equipment.
• The parts warranty and the labor warranty, each with its length in writing.

Check whether the indoor coil and the refrigerant line set are being replaced along with the outdoor unit. A quote that swaps only the outdoor unit looks cheaper and may not deliver the rated efficiency.