HVAC Repair St. Louis: $144 to $451 Nationally + Permits

We found no St. Louis-only HVAC repair price, so repair rows are national except Angi's St. Louis radiator figure. The permit row is local.

Do this now: heat or AC out in St. Louis

1. Smell gas? Leave the house and call 911 or Spire from outside. Do not flip switches or look for the leak. A carbon monoxide alarm means the same: get out, then call 911.
2. Check the thermostat mode and setpoint, the furnace or air handler switch and the breaker. If a breaker trips again, stop resetting it.
3. Check the filter and replace it if it is clogged.
4. No AC in the heat: the CDC says that above 90 F indoors a fan can raise body temperature. Get older adults, infants and anyone with heart or lung disease somewhere air-conditioned; dial 2-1-1 to find a place.
5. No heat in a freeze: open sink cabinets and drip faucets on outside walls (Red Cross). See frozen pipes.
6. Never heat the house with the oven or stove, the CDC says.

Is it an emergency? St. Louis heat and cold by the numbers

St. Louis gets both extremes: Lambert airport averages 47.1 days a year at or above 90 F and 84.9 days at or below 32 F, NOAA's 1991 to 2020 normals show, and the National Weather Service lists the all-time high as 115 F on July 14, 1954. No cooling in a heat wave or no heat in a freeze is an emergency, especially with older adults, infants or anyone with heart or lung disease at home. Ready.gov says to call 911 for heat stroke signs such as a body temperature above 103 F or confusion. A noisy unit that still works can wait for a weekday. After-hours prices are on emergency HVAC repair.

AC repair in St. Louis

AC repair in St. Louis typically costs $172 to $664, HomeAdvisor's 2026 national range (about $417 is typical), and HomeGuide's is $150 to $650; no publisher lists a St. Louis-only AC price. Common fixes: a capacitor at $120 to $475 and a refrigerant leak at $225 to $1,600, HomeAdvisor says. HomeGuide notes that only EPA Section 608 certified technicians may buy and handle refrigerant, and an AC that keeps needing refrigerant has a leak. With 47.1 days a year at 90 F or hotter, St. Louis systems work hard; HomeAdvisor says to consider replacing a unit over 10 years old, one that uses R-22, or one where the repair cost times its age tops $5,000. Ameren Missouri's Peak Time Savings pays a $50 smart thermostat enrollment bonus plus $25 a year for homes with central AC or a central furnace. Symptoms and fixes: AC repair and AC not cooling.

Boiler repair in St. Louis

Boiler repair in St. Louis falls in the national range of $190 to $660 that HomeAdvisor reported in 2026, with an average of $425, and Angi's St. Louis guide puts radiator repair at $100 to $650. Two local points: the City's Mechanical Contractors Board licenses pipefitters as well as mechanical contractors, so ask which license the technician holds; and Ameren Missouri's Peak Time Savings thermostat program does not accept boiler or radiant systems. City homeowners 60 or older can apply to the Senior Minor Home Repair Program, which covers heating repairs, at (314) 612-5918. Pressure, leaks and banging pipes are covered on boiler repair.

Furnace repair in St. Louis

Furnace repair in St. Louis runs $133 to $505, HomeAdvisor's 2026 national range. The City requires a mechanical permit to install a furnace and issues it only to City-licensed mechanical contractors. The full guide, with no-heat steps and repair programs, is furnace repair in St. Louis.

St. Louis mechanical permits and licenses

Mechanical permits in the City of St. Louis go only to City-licensed mechanical contractors, with a $25 application fee per permit plus a fee schedule; the permit page names furnaces. The Mechanical Contractors Board licenses mechanical contractors and pipefitters. There is no public license search on the board pages, so call the Building Division at (314) 622-3313, or look up past permits at your address with the City's permit search.

Help paying for heating and cooling repairs in St. Louis

• LIHEAP and ECIP (Missouri energy assistance): in the City, apply through the Urban League of Metropolitan St. Louis, (314) 615-3632. In St. Louis County, CAASTLC, (314) 446-4420.
• Senior Minor Home Repair Program: heating and cooling repairs for City homeowners 60 or older, (314) 612-5918.
• Healthy Home Repair Program: health and safety repairs for income-qualified owner-occupants, 314-657-3888; expect a waitlist.
• Weatherization: Urban League, 314-615-3600 (City); CAASTLC, 314-863-0015 (County).
• Ameren Missouri HVAC PAYS: rebates on high-efficiency HVAC, with the rest repaid on your electric bill at 3% interest and no credit check. Renters can take part.

No federal credit helps with a new system in 2026: the IRS says 25C does not apply to property placed in service after December 31, 2025. Compare AC replacement cost and heat pump installation cost.

Local rules, programs and climate for St. Louis, from the official city, utility, state, Census and NOAA pages listed under Sources.

Questions to ask a St. Louis HVAC company

1. Are you licensed by the City's Mechanical Contractors Board, and what is the license number?
2. What is the diagnostic or trip fee, and is it credited toward the repair?
3. If the system is past 10 to 15 years, will you price a repair and a replacement side by side, with any Ameren rebate?
4. Will you pull the mechanical permit if equipment is replaced?
5. Can I see proof of insurance and a written price before work starts?

More St. Louis guides

Leaks from the AC drain or water heater: plumber in St. Louis. Damp ducts or mold: mold removal in St. Louis. Compare HVAC repair in Kansas City and HVAC repair in Chicago, or start at the national HVAC repair guide. Calls go to an independent company that serves your area and takes this kind of job (how calls work).