What you're probably noticing right now
It's likely one of two things. Either the unit outside your house is running almost constantly and the house still isn't cooling past 78, or you've had a contractor out and you're staring at a quote that seems high and wondering if it's fair. Both are common around Nixa in July and August, when the humidity off the Ozarks sits on top of the heat and asks your AC to do two jobs at once: cool the air and wring the water out of it.
Southwest Missouri summers are long and sticky. A unit that's marginal in June is often flat-out losing by August. That's usually when people start calling contractors, which also means it's the busiest season for scheduling and the easiest time to get rushed into a decision.
The age and type of house matters here
A lot of homes in and around Nixa were built from the 1970s through the 2000s, plus a steady wave of newer construction as the town has grown. Older homes often still have original ductwork sized for a smaller unit or a different layout after additions and finished basements. A contractor who just swaps in a new outdoor unit without checking the ducts and the load calculation for your specific house is guessing. That guess usually shows up later as short cycling, uneven rooms, or a system that runs constantly without ever quite catching up.
If you've had rooms added, a garage converted, or windows replaced since the AC was installed, mention it. Those changes affect how much cooling the house actually needs, and a contractor who doesn't ask about them isn't doing a full job.
More on this from Hiring An AC Contractor In Nixa.
What you can check before you call anyone
Start with the filter. A clogged filter is still the single most common reason a system underperforms, and it costs almost nothing to fix. Check it monthly during cooling season, more often if you have pets.
Walk around the outdoor unit. It needs clear space, at least a foot or two on all sides, for airflow. Leaves, mulch, grass clippings, and the fluff from cottonwood trees all build up on the coil fins over a season and choke the unit's ability to shed heat. A garden hose, sprayed gently from the inside out, can clear light debris. Anything more than that, or any bent fins, is past the homeowner stage.
Listen to the unit. Rattling, grinding, or a hard click followed by silence are all signs to stop troubleshooting yourself and get someone out. Refrigerant lines, electrical components, and the compressor itself are not places to experiment.
Questions worth asking before you sign anything
Ask whether they're doing a load calculation for your house or just matching the size of the unit you already have. Matching old to old is easy and sometimes wrong, especially in homes that have been modified over the years.
Ask what happens to your ductwork. In this area, crawlspace and attic ductwork takes a beating from humidity and temperature swings, and leaky or crushed ducts can waste a large share of your cooling capacity before it ever reaches a room. A contractor who's willing to check duct condition, not just the equipment, is thinking about the whole system.
Ask about the warranty in plain terms: what's covered, for how long, and whether it requires the installing contractor to do the work if something fails. Get it in writing rather than taking a verbal assurance.
Where this stops being a homeowner decision
Refrigerant work, electrical connections at the disconnect box, and anything involving the compressor require a licensed contractor, full stop. Missouri also has requirements around refrigerant handling that a homeowner can't legally work around even if they wanted to.
If you're getting quotes that vary wildly for what sounds like the same job, that's usually a sign one contractor did a load calculation and duct inspection and another didn't. The cheaper number often reflects less work being done up front, not a better deal. Ask what's included before comparing prices side by side.
And if a system is more than fifteen years old and starting to need repairs every summer, it's worth getting a straight answer about whether you're paying to patch something that's on its way out anyway. A contractor who tells you to wait another year, if that's the honest answer, is worth more than one who doesn't.