HVAC Repair in St. Louis, MO
Homes here need heat from October through April and cooling from May through September. If your system quits, tell us what it's doing and a licensed contractor who covers St. Louis will get in touch.
Tell us about the job
It takes about a minute.
St. Louis runs its system almost year round
Your furnace works October through April here, and the air conditioner takes over May through September. That leaves the equipment little time off, and winter nights averaging 26°F mean the burner is cycling on and off most of the night to keep up. Each cycle is a start, and starts wear on the igniter and the flame sensor. Summer afternoons near 87°F push just as hard the other way, running the compressor long hours to keep the house cool.
Most homes here heat with gas, so a furnace that won't light is the common winter call. St. Louis also sees its share of wind and ice. The area has logged 28 damaging wind events and 9 winter storms over the past ten years, and storms mean power loss. Close to one in five Missouri households went at least a day without power in 2024, and when the power drops mid-storm, the system needs to come back on and run correctly once it's restored.
- 7 months
- October through April, your system heats
- 5 months
- May through September, it cools
- 26°F
- the average winter night it heats against
- 87°F
- the average summer afternoon it cools against
NOAA nClimDiv, 1991–2020 normals
A new furnace and air conditioner would cut about $200 a year off heating and cooling for a typical St. Louis home.
Estimates for a typical St. Louis home, compared with an older unit built to the previous federal minimum, from EIA household energy data, Missouri fuel prices and NOAA climate normals. Your home will differ.
Repair makes sense when one part has failed.
Replacement makes sense when the furnace's heat exchanger is cracked, the air conditioner's compressor has failed, or repairs keep coming.
- Why is my heat not working?
- Start with the thermostat and the filter. If the thermostat is set to heat and a few degrees above room temperature but nothing happens, check the filter next, since a clogged one can make a furnace shut itself off before it overheats. If the furnace has a pilot light or an igniter you can see, check whether it's lit or glowing. If the breaker for the furnace has tripped, or a gas valve got bumped shut, that alone can explain a cold house. When none of that explains it, especially with nights averaging 26°F here in the winter, a contractor should look at it soon rather than wait.
- Why is my system running but not cooling the house?
- The blower may be moving air while the part that actually cools it, the coil or the compressor outside, isn't doing its job. A dirty air filter is the first thing to check, since it chokes off airflow across the coil. Next, look at the outdoor unit. If the fan isn't spinning, or the coil is caked with dirt or covered in ice, the system can't reject heat and the air coming out of your vents will feel warm or barely cool. A refrigerant leak causes the same thing and that's not something to chase yourself. If the filter's clean and the outdoor unit looks normal, it's time to call someone, especially with afternoons here running near 87°F.
- What can I check before calling for HVAC repair?
- Check the thermostat first. Make sure it's set correctly, has power or a fresh battery if it uses one, and is actually calling for heat or cooling. Check the air filter next and replace it if it's gray or clogged, since restricted airflow causes problems in both winter and summer. Check your breaker panel for a tripped breaker, and if you have gas heat, make sure the gas valve is open. If the outdoor unit is covered in leaves, ice, or debris, clear it. If you've done all that and the system still isn't working, a contractor will need to look at it, and telling them what you already checked will save time.