What is central air conditioning?
Central air conditioning is a closed refrigerant loop that absorbs heat from the air inside your home and releases it outside. The indoor coil (evaporator) absorbs heat as refrigerant evaporates; the outdoor unit (condenser + compressor) pumps that heat outside and resets the cycle. The blower then circulates the cooled, dehumidified air through your ductwork.
Because it moves heat rather than creating cold, an AC's real job in a humid St. Louis summer is twofold: lower the temperature and pull moisture out of the air. A system that's oversized cools fast but never runs long enough to dehumidify — which is why bigger is not better.
When do you need to think about it?
Most homeowners only think about their AC when it stops cooling. The better moments to act are: before peak summer (a tune-up catches weak capacitors and low charge), when bills climb without a weather reason, or when a system passes 12–15 years and repairs start stacking up.
- Warm air from the vents or long run times that never satisfy the thermostat
- Ice on the refrigerant lines or indoor coil (often low charge or airflow)
- Rising humidity indoors even while the AC runs
- A system using R-410A refrigerant that's leaking (see the glossary and the refrigerant note below)
What goes wrong (failure modes)?
Most 'the AC is broken' calls trace back to a handful of issues: a failed run capacitor, a refrigerant leak, a dirty coil restricting airflow, or an oversized system that short-cycles. The expensive mistake is replacing a whole system when a component repair would do — or installing a like-for-like unit without checking the duct system feeding it.
How Degenhardt approaches it
We size with a load calculation rather than a rule of thumb, verify airflow through your existing ductwork (our Local 36 sheet-metal background is the reason we look here first), and confirm refrigerant charge by measurement, not guesswork. As a Daikin Comfort Pro and Rheem dealer, we match the equipment to your home and budget — and tell you when a repair is the smarter call.
Proof: family-owned and serving South St. Louis since 1984; NATE-certified technicians; Sheet Metal Workers' Local 36 union training; free, no-obligation written estimates.
Frequently asked questions
Most systems last 12–15 years here; humidity and long cooling seasons push hard-working units toward the lower end. Annual maintenance is the biggest factor in reaching the upper end.
Common causes are a failed capacitor, low refrigerant from a leak, a frozen or dirty coil, or restricted airflow. It's worth a same-day diagnostic in a heat wave — call before it becomes a full breakdown.
No. An oversized AC cools the air fast but shuts off before it removes humidity, leaving your home cool but clammy and cycling the equipment harder. Correct sizing from a load calculation matters more than tonnage.