What you're probably noticing
Your new air conditioner is in, the installer is packing up, and the house feels fine for now. But a lot of what determines whether that system runs well in July, or limps along and dies early in year six, happened in three steps most homeowners never see: pulling a vacuum on the line set, charging the refrigerant, and setting the airflow across the coil. None of that shows up on the invoice as a line item, but it shows up in your utility bill and in whether you're calling for a repair during the first heat wave.
If your install happened fast, in a few hours with minimal fuss, that's not automatically a bad sign. But if nobody mentioned a vacuum pump, or you never heard a gauge set click onto the lines, it's worth asking questions before the final payment goes out.
Why evacuation matters more here than it would in a dry climate
Southwest Missouri humidity is the whole reason evacuation isn't optional. Nixa sits in a part of the country where summer dew points regularly sit in the sticky range, and any moisture left in the refrigerant lines when the system is sealed up becomes a problem fast. Moisture mixed with refrigerant forms acids that eat away at compressor components from the inside. In a dry climate the consequences of a rushed evacuation show up slower. Here, with the air already loaded with water vapor, a sloppy job tends to surface within the first couple of cooling seasons.
You can't check this yourself after the fact. Evacuation happens before the system is charged, pulling the line set down to a deep vacuum and holding it there long enough to prove no moisture or air remains. The only real check available to you as a homeowner is at the time of install: ask if they're pulling a vacuum and for roughly how long, and whether they're using a micron gauge rather than just running the pump for a fixed number of minutes and calling it done.
More on this from Evacuation, Charge And Airflow, The Three On-Site Settings.
Charge and the stop-and-go nature of Ozark summers
Nixa's summers aren't a steady grind of heat the way some parts of the country are. You get stretches of 95-degree days with high humidity, then a cold front drops temperatures and humidity for a few days, then it's back. That kind of swing means your system is cycling on and off a lot rather than running continuously, and a correctly charged system handles those start-stop cycles far better than one that's slightly over or under charged.
An undercharged system struggles to pull humidity out of the air, something that matters a lot in a region where summer air already feels heavy. An overcharged system can cause the compressor to run hotter than it should and shortens its life. Charge has to be checked against the specific outdoor temperature at the time of install, using gauges and often a superheat or subcooling measurement, not just topped off until pressure looks reasonable. This is squarely not a homeowner task. What you can do is ask whether they measured superheat or subcooling and wrote the numbers down somewhere, rather than eyeballing it.
Airflow and what older Nixa homes do to a new system
A lot of housing stock around Nixa and the surrounding Christian County area was built in the 80s and 90s, with ductwork sized for the equipment and insulation standards of that era. When a new, more efficient unit goes into an older duct system, airflow across the coil can end up too low if the technician doesn't check and adjust for it. Low airflow makes the coil run colder than it should, which risks icing up the coil during long summer cooling runs and reduces how much moisture the system actually removes from the air.
This is one spot where you can do a basic check yourself. Feel the airflow at your supply registers once the system has been running a while on a hot day. It should feel like a steady, noticeable stream, not a weak trickle. If some rooms feel fine and others barely get any air, that's worth mentioning. You can also check your return air filter is the right size and not an undersized one jammed into an oversized opening, which happens more often than you'd think in homes that have had ductwork modified over the years.
What's reasonable to ask before the crew leaves
You don't need to understand refrigeration cycles to ask good questions. Ask what the vacuum reading was and how long it held. Ask what the charge method was and whether superheat or subcooling numbers were recorded. Ask whether airflow was measured, not just estimated, especially if your ductwork predates the new system by a couple of decades. A straight answer with a number attached is a good sign. A vague answer about everything being
Falling for a quick walkthrough without specifics isn't a reason to assume something's wrong, but it is a reason to ask for the paperwork. Reputable installers in this area keep records of these readings precisely because of how humid summers here make sloppy installs show up fast. If those numbers aren't available, it's reasonable to ask for them in writing before you consider the job finished.