St. Louis, MO · 2026
AC repair in St. Louis
By the HeatAndAirCost editors · Last updated October 5, 2026 · How we research prices
Short answer
AC repair in St. Louis typically costs $150 to $650, with the national average near $350 and a $75 to $200 fee to find the problem before parts are ordered. NOAA's normals show a normal summer high near 88°F here, and the Mississippi River's humidity makes that heat feel heavier on a cooling system than the number alone suggests.[1]
St. Louis city neighborhoods
The independent, licensed contractors in our network cover these parts of the city and nearby county communities:
Central West End · The Hill · Soulard · Tower Grove South · Dogtown · Lafayette Square · Shaw · Benton Park · Clayton · University City · Kirkwood · Webster Groves · Maplewood · Richmond Heights
We are not a contractor and do not have an office in St. Louis. We connect you with independent, licensed HVAC contractors who serve these areas.
Common AC trouble in St. Louis homes
Humidity and an older housing stock combine to produce a fairly specific set of summer AC complaints in the city.
- Air comes out warm instead of cool. In older homes running a single system across multiple floors, a struggling compressor or a refrigerant leak often shows up first as warm air from vents on the floor farthest from the unit.
- Upstairs rooms never cool down. Brick two- and three-story houses with retrofitted ductwork or a single window unit frequently cool the main floor fine while upper rooms lag behind, especially on humid afternoons.
- Loud buzzing from the outdoor unit. An aging compressor or a loose electrical connection inside an older outdoor unit can buzz noticeably before it fails outright, and it is worth having checked rather than ignored.
River humidity meets an old housing stock
At the Cahokia-St. Louis airport station, NOAA's 1991 to 2020 normals show a summer high around 88°F and roughly 1,476 cooling degree days a year, against 4,547 heating degree days. The result is a true four-season climate with a summer that is shorter than the southern Plains but still hot and consistently humid.
St. Louis is its own independent city, separate from St. Louis County, and much of the city's housing is old brick stock that was never built with central air in mind. Retrofitted ductwork, window units, and single-zone systems trying to cool multiple floors are all common, and they tend to cool unevenly once the Mississippi's humidity settles in for the summer.
A system fighting both heat and humidity runs long hours, and long run times are what wear out capacitors, contactors, and condensate pumps. Replacing the filter and confirming the condensate line drains freely are two things worth checking before calling anyone out.
What St. Louis mechanical licensing covers
The City of St. Louis's Mechanical Contractors Board of Examiners reviews licensing qualifications for mechanical contractors and pipefitters doing regulated mechanical work in the city. The city's mechanical licensing code applies only to commercial structures, though, and does not apply to residential buildings with six or fewer dwellings or to work with an aggregate mechanical contract price of $25,000 or less.
A house or small apartment building therefore falls outside that code. Ask a St. Louis contractor which permits your job needs and confirm the details with the city before work begins.[3]
St. Louis by the numbers: climate, energy prices, homes and contractors
Federal figures for St. Louis, each linked to its source and dated. They describe local conditions; they are not quotes and do not rate any business.
How hard St. Louis's climate works an HVAC system
Degree days count how far each day's average temperature sits from 65°F. Heating is the bigger job here. A normal year carries about 3.1 times as many heating degree days as cooling degree days, so the furnace or heat pump logs far more run time than the air conditioner. At this station the normal summer high is 88°F (June through August) and the normal winter low is 27°F (December through February).
Source: NOAA NCEI U.S. Climate Normals, 1991 to 2020, station CAHOKIA ST LOUIS AP (USW00003960), 6.5 miles from the Census center point of St. Louis. Data as of 1991-2020. Retrieved October 5, 2026.
What electricity and natural gas cost in Missouri
Homes in Missouri paid an average of 13.49 cents per kilowatt-hour in 2025, 22% below the U.S. average of 17.30 cents. Natural gas delivered to homes averaged $16.86 per thousand cubic feet in 2024, 16% above the U.S. figure of $14.50. An air conditioner runs entirely on electricity, so the state rate sets the price of every extra hour of cooling. If a summer bill jumps without a matching heat wave, our high electric bill from AC guide lists the checks to run first.
Source: U.S. Energy Information Administration, Missouri state energy profile and electricity data browser (average retail price, residential sector), and natural gas prices by state (price delivered to residential consumers). The $ per 1,000 kWh figure is the state average price times 1,000. Data as of 2025 / 2024. Retrieved October 5, 2026.
How St. Louis homes heat, and how old they are
Utility gas heats 67% of occupied homes in St. Louis and electricity heats 31%, so a gas furnace is the most common setup. The usual gas-furnace failures are covered in furnace not turning on. Half of the city's housing units were built in 1938 or earlier, and 86% predate 1980, while 3.7% went up in 2010 or later. Our HVAC lifespan guide explains how long furnaces, air conditioners and heat pumps typically last.
Source: U.S. Census Bureau, American Community Survey 2020-2024 ACS 5-year estimates for St. Louis city, Missouri, table B25040 (House Heating Fuel) and table B25034 (Year Structure Built). Survey estimates carry margins of error; percentages are our arithmetic on the published counts. Data as of 2020-2024. Retrieved October 5, 2026.
Plumbing, heating and air-conditioning businesses in St. Louis city
The Census Bureau counted 58 plumbing, heating and air-conditioning contractor establishments in St. Louis city in 2023, with 1,265 employees between them. The industry code (NAICS 238220) includes plumbers and counts business locations, not licenses, so treat it as an upper bound on HVAC firms. It names no company; check any contractor's license before you hire.
Source: U.S. Census Bureau, County Business Patterns 2023, NAICS 238220 (program overview). Payroll per employee is annual payroll divided by employees. Data as of 2023. Retrieved October 5, 2026.
What HVAC technicians earn in the St. Louis, MO-IL area
The median heating, air-conditioning and refrigeration mechanic in the St. Louis, MO-IL metro area earned $63,000 a year in May 2025, 3% above the national median of $61,010. An invoice adds parts, travel, overhead and margin to that wage, so read it as context for labor rates, not a price; our service call cost guide breaks a bill down.
Source: U.S. Bureau of Labor Statistics, Occupational Employment and Wage Statistics, May 2025, metropolitan areas, occupation 49-9021, area code 41180 (data file). The U.S. comparison uses the national estimate from the same release. Data as of May 2025. Retrieved October 5, 2026.
Know a fair price first
Before you accept any AC repair quote in St. Louis, compare it against our researched national ranges on the AC repair cost page. If your system is older and the quote is steep, run the $5,000 rule and check HVAC replacement cost before you commit[2].
Before you call: try the free checks
Not every cooling problem is a repair. Work through the no-tool checks on our AC not cooling and AC blowing warm air guides, and read how to choose an HVAC contractor before you hire.
More guides for St. Louis homeowners
Start from the symptom you are seeing on the HVAC troubleshooting hub or the HVAC symptoms index, then check the fair price for the repair you are quoted.
Other cities we cover
Labor rates and the failures that show up first change with the climate, so the city pages are written one at a time rather than stamped out. Every metro we have published so far is on the service areas hub.
Nearest city guides
- AC repair in Indianapolis, IN (233 miles away)
- AC repair in Kansas City, MO (234 miles away)
- AC repair in Nashville, TN (255 miles away)
- AC repair in Chicago, IL (259 miles away)
- Furnace repair in Madison, WI (311 miles away)
- AC repair in Cincinnati, OH (311 miles away)
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HeatAndAirCost connects homeowners with independent, licensed HVAC contractors. The service is free to you: contractors pay us, and that never changes what you pay. We are not a contractor, we do not perform repairs, and the prices on this site are researched ranges, not quotes.
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- Researched price ranges, not quotes
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Is this covered by a home warranty?
A home warranty is an annual service contract that pays to repair or replace covered home systems and appliances when they fail from normal use, in exchange for a monthly premium and a fixed service fee per visit. It does not cover a failure that has already happened or a fault that existed before the plan started, so it only helps if it is in place before the breakdown.
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People also ask
St. Louis AC repair FAQs
What does AC repair run in St. Louis?
Plan on $150 to $650 for most jobs, with a national average near $350 and a $75 to $200 diagnostic fee up front. A capacitor repair usually costs $250 to $400, and a compressor replacement runs $1,800 to $2,800. Use these 2026 national figures as a baseline to weigh a St. Louis quote against, not as the quote itself.
Does old brick housing in St. Louis make AC repair harder?
Yes, in a specific way. Many city homes were built before central air was common, so systems are often retrofitted into tight spaces or asked to cool multiple floors through older ductwork, which can make diagnosing an uneven-cooling complaint take longer.
Why is humidity such a problem for AC here even on days that aren't that hot?
The Mississippi River keeps humidity high through most of the summer, and a cooling system has to remove that moisture as well as lower the temperature. A unit low on refrigerant or with a dirty coil falls behind on humid days well before the thermometer alone would suggest trouble.
Is there a St. Louis license for residential HVAC contractors?
The City of St. Louis's mechanical contractor licensing code applies to commercial structures and does not apply to residential buildings with six or fewer dwellings. Ask your contractor which permits the job needs and confirm them with the city.
What is the $5,000 rule for HVAC?
The $5,000 rule multiplies a unit's age in years by the repair estimate in dollars; cross $5,000 and replacement usually makes more financial sense than repair. Take a 5-year-old AC quoted at $300: that scores 1,500, an easy repair. A 10-year-old unit quoted at $550 scores 5,500, just over the line, which is where replacement starts to look like the better bet.
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