Air Conditioning in St. Louis, MO

Air conditioning in St. Louis has to do two jobs at once: cool the house and pull moisture out of it. St. Louis sits in ASHRAE Climate Zone 4A, mixed-humid, and the National Weather Service logged 49 days at or above 90°F here in 2025, along with 1,904 cooling degree days against a 1,713 normal. Choosing the right service starts with matching your symptom to the right page.

Which AC service fits the problem you have?

Match what you see to the job, then follow the link for detail.

If the system dies at night or over a weekend, use emergency AC repair. We are open 24 hours, and we offer same-day service when the schedule allows.

When does an older air conditioner stop being worth fixing?

Around the 15-year mark, the repair quote starts to matter more than the repair. Contractor sources put air conditioner life at about 15-20 years with routine maintenance. A failed capacitor on a healthy unit is a small repair. A failed compressor or a leaking coil on an old one deserves a replacement quote beside it.

Refrigerant changes the math. R-22 production and import ended on January 1, 2020, so service on an R-22 system relies on reclaimed or stockpiled supply, and a recharge can cost more than it saves. If you suspect a leak, read the refrigerant leak repair page before you pay for a top-up.

Repair comes first here, and when a new unit is the better buy, we show you the numbers behind that.

What should a new central AC be rated and sized for?

A new split-system AC must meet DOE's 2023 minimum of 13.4 SEER2, which equals 14 SEER, for units under 45,000 Btu/h in the North region that includes Missouri. Higher ratings cost more, so decide what you will actually save on a bill before paying for them. New residential split systems built since January 1, 2025 use refrigerant under 700 GWP, usually R-454B or R-32.

Size matters more than rating. A unit that is too big cools quickly, shuts off early and leaves the air damp, which is the complaint behind many St. Louis summers. Insist on a load calculation before anyone sizes the equipment. Then expect a permit and an inspection, since St. Louis County requires a permit to install or replace air-conditioning systems.

How does a spring check change the summer?

A spring check catches the slow failures before the first 90-degree week: a weak capacitor, a matted condenser coil, a draining line that has started to back up. Book it in April or May, not during the first heat wave when every shop is busy. AC maintenance describes what the visit covers.

North county adds its own load. Cottonwoods shed heavy fluff in late spring near the river bottoms, and it packs into condenser coils right before the first 90-degree week. Humid July evenings fill the condensate drain, which is why a clogged line often shows up as water around the indoor unit. Between visits, keep two feet clear around the outdoor unit and change the filter on schedule; our filter guide explains the timing.