AC Installation Cost in Great Falls, Montana
Our 2026 estimate for new AC installation in Great Falls, MT is $3,500 to $7,900. That puts Great Falls 17% below the national average, mainly because of lower local labor costs.
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Great Falls Weather and HVAC Load
Great Falls logs 6,942 heating degree days and 421 cooling degree days in a normal year, based on the closest NOAA weather station. Heating is the bigger job here. The AC still runs every summer, but it works far fewer hours than the furnace does. Count on roughly 143 nights below 32°F and 25 afternoons past 90°F in a typical year. Snowfall averages about 66 inches. On the cooling side, a 2,000 sq ft house here usually needs around 2.5 tons. A tight, well-insulated house may get by with half a ton less.
| Heating degree days / year | 6,942 |
|---|---|
| Cooling degree days / year | 421 |
| Nights at or below 32°F | 143 |
| Days above 90°F | 25 |
| Average low / high | 35.1°F / 59°F |
Great Falls Housing Stock
Census figures put the median build year in Great Falls at 1965, so a typical house here has about 61 years on it. A lot of these homes are on their second or third system by now. The ductwork is usually original, and leaky joints are common. Great Falls has roughly 18,000 owner-occupied homes, or 68.4% of households. The median home value is $237,400, and median household income is $63,934. We use both figures to adjust labor and pricing for this page.
NOAA storm reports for Cascade County show 12 hail days and 22 days with damaging thunderstorm winds over the six years from 2020 to 2025. The largest hail reported was 3 inches across. Hail flattens the thin aluminum fins on condenser coils and cuts airflow. After a big storm, take a look at the outdoor unit; homeowners insurance often covers the damage. In Great Falls, 20% of residents are 65 or older. For older adults, a house with no heat in January or no AC during a heat wave is a medical risk. Mention it when you call, since many companies put those calls first.
When It Makes Sense
- The AC is 12 to 15 years old or more
- It still runs on R-22 refrigerant
- Summer electric bills keep going up
- It has had more than one refrigerant leak
What Moves the Price
- Whether the coil and line set also need replacing
- Electrical work such as a new disconnect, breaker or wiring
- SEER2 rating and whether the compressor is single-stage or variable-speed
- Tonnage, based on house size and local climate
- The pad, permit and refrigerant (R-410A or the newer R-454B)
For Great Falls we lowered the national figures about 17%, based on local income, home values and climate-based equipment sizing. Get at least three written quotes; real bids can land outside this range.
What the Quote Should Cover
- Startup, an airflow check and warranty registration
- Removing the old condenser and coil
- Refrigerant charge and a leak test
- The new condenser, coil and, if needed, line set
- The electrical disconnect and wiring
Montana Permits, Efficiency Rules and Rebates
Montana falls in the DOE's North region. New split central air conditioners must meet at least 13.4 SEER2, and heat pumps sold anywhere in the U.S. need 14.3 SEER2 and 7.5 HSPF2. Equipment replacements in Great Falls generally need a mechanical permit, and a reputable contractor will pull it for you. Ask for their Montana license or registration number and a certificate of insurance with the quote. The federal 25C tax credit ended for equipment installed after December 31, 2025, so incentives now come mostly from utilities and state programs. Check your electric and gas utility's rebate page before you pick equipment.
Before You Hire
- Ask for a Manual J calculation. "Same size as the old one" isn't sizing.
- Fall and early spring installs often come with better pricing and shorter waits.
- Buy the condenser and coil as a matched set, or you may void the manufacturer warranty.
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AC Installation Questions from Great Falls Homeowners
How much is new AC installation in Great Falls?
Plan on $3,500 to $7,900, with most jobs near $5,900. Equipment efficiency, house size and the condition of the ducts and wiring decide where your quote falls.
When is the best time to schedule new AC installation in Great Falls?
Between late spring and early fall. Great Falls averages 143 freezing nights a year, and heating calls spike from November through February.
What size AC do I need?
It depends on square footage, insulation, windows and climate. The rough rule is a ton for every 450 to 650 sq ft, but only a Manual J calculation gives you a real number.
How long does a new AC last?
With yearly maintenance, 12 to 17 years. Salt air and extreme heat shorten that.
AC Installation Near Great Falls
Sources: U.S. Census Bureau ACS 5-year estimates 2019-2023 and 2024 population estimates; NOAA NCEI U.S. Climate Normals 1991-2020, station Great Falls 16st; NOAA Storm Events Database 2020-2025, Cascade County. Prices are our estimates, not contractor quotes. Updated 2026.