The old house gets hot upstairs in July
If you own one of the older homes around Rountree, Walnut Lawn, or the brick bungalows near downtown Springfield, you already know the pattern. Window units in three rooms, a box fan in the hallway, and the second floor still sits ten degrees warmer than the first by August. These houses went up before central air was standard, built with gravity furnaces or steam radiators and no ductwork anywhere in the walls. Adding central air sounds simple until you realize there's no path for the air to travel.
Springfield summers run hot and sticky, with July and August regularly pushing into the 90s with humidity that makes it feel worse. A house with no ducts wasn't designed to fight that. It was designed for cross breezes and tall ceilings. Retrofitting central air into that kind of structure is a real project, and it's worth understanding where the difficulties actually show up before you get quotes.
Where the ducts would even go
The first problem is physical space. Houses built in the 1920s through the 1940s, common in the older Springfield neighborhoods, have plaster walls, narrow closets, and no chases built for mechanical runs. There's no cavity waiting for a duct. Contractors usually end up running ducts through closets, boxing them into corners of rooms, or dropping a soffit along a hallway ceiling. None of that is free, and none of it is invisible once it's done.
You can do some of this scouting yourself before you call anyone. Walk the house and look for any existing chases: an old coal chute, a boarded-up dumbwaiter shaft, a closet stacked directly above another closet on both floors. Those vertical paths are gold for a retrofit because they let a contractor run trunk lines without opening walls everywhere. If you don't see any obvious stacked space, don't be surprised when the estimate includes some carpentry and drywall work along with the mechanical installation.
More on this from Adding Central Air To A House Built Before Ducts Existed.
What the attic and crawlspace tell you
A lot of these older Springfield homes have a basement or a stone foundation with a shallow crawlspace, not a slab. That matters because it gives a contractor somewhere to run supply trunks before branching up into the rooms above. If your house has a full basement with decent headroom, that's good news. If it's a tight crawlspace with four feet of clearance and exposed limestone, the work gets slower and the price goes up, because an installer is working on their back the whole time.
Check your attic too. Houses with a finished or low-pitched attic have less room to snake ductwork down into the second floor. Houses with a steeper roofline and open rafters give more flexibility. None of this is a job to attempt yourself beyond looking and taking notes. But knowing what's up there before someone gives you a number helps you understand why one estimate is twice another.
The furnace question nobody mentions at first
Many of these older homes still run a boiler with radiators, or a very old gravity furnace that was converted decades ago to forced air with minimal ductwork for a single zone. Adding central air often means replacing the whole heating and cooling system together, not bolting an AC unit onto whatever is already there. An old boiler can't just get an air conditioner wired alongside it. That's a bigger, more expensive project than most homeowners expect going in.
This is also where sizing matters more than people think. A contractor needs to calculate the actual heating and cooling load for your specific house, factoring in the single-pane windows, the lack of wall insulation common in homes from that era, and the ceiling heights. An oversized system cools the house fast but leaves it clammy, which is its own problem in Missouri humidity. This load calculation is not a homeowner task. It requires someone walking the house and doing the math room by room.
What you can reasonably check yourself
Before calling anyone, walk your own house with a notepad. List every closet, every stacked space, and anything in the attic or basement that looks like leftover mechanical chase space from a previous renovation. Note whether your current heat source is a boiler, a very old furnace, or something already updated. Take photos of your electrical panel too, since central air usually needs added capacity there, and an older home may still have a panel that was never upgraded past 100 amps.
Once you've got that information, the rest is a job for someone who installs these systems regularly in homes like yours around Springfield. They'll know which neighborhoods tend to have crawlspaces versus basements, which old chases show up again and again in certain house styles, and how much slack to leave in an estimate for the unexpected plaster repair. That's the point where a homeowner's job ends and a contractor's begins.