How Does Central AC Work? What to Know Before Replacing

• Published: 04/09/25
• Updated: 05/28/25

If you’re a homeowner in South Carolina considering a new cooling system (or wondering if your aging air conditioner is due for a replacement) you’re likely asking: how does central AC work, and is it still the right choice for your home?

Understanding the basics of central air and heat helps you make smarter decisions when comparing options like central AC vs mini splits, planning a central AC installation, or budgeting for long-term comfort and efficiency.

Let’s break it all down.

What Is Central Air and Heat?

Central air is a whole-home system designed to circulate cool air through ductwork and vents. Often paired with a heating system (like a furnace or heat pump), these systems are a popular solution for maintaining consistent indoor temperatures year-round.

If your home has ductwork and you want even cooling in every room, central air is likely the most efficient choice. When paired with programmable thermostats and modern energy-saving features, central air can be both effective and cost-efficient.

How Does Central AC Work?

At a high level, your central air conditioner pulls warm air from your home. It then cools it using a refrigeration cycle, and circulates the cooled air back into your living space.

Here’s how the cycle works:

1. Thermostat Activation: When indoor temperatures rise above your set point, the thermostat signals the system to turn on.
2. Warm Air Is Pulled In: Air from your home is pulled through return vents and passed over the evaporator coil located inside the indoor unit.
3. Heat Is Removed: The refrigerant inside the evaporator coil absorbs the heat.
4. Heat Is Released Outside: The refrigerant flows to the outdoor unit where the compressor pumps it through the condenser coil, releasing the heat outside.
5. Cool Air Is Circulated: The cooled air is pushed through ducts and vents back into your home.

It’s a continuous cycle. When all components work together as designed, the system delivers steady, even cooling throughout the home. Understanding this process can help you spot issues early or make more informed choices when it’s time to install or upgrade.

Central AC Components That Keep You Cool

Let’s look at the key components to understand how the system works together:

• Thermostat: Acts as the control center. It senses the temperature inside your home and tells the system when to turn on or off.
• Evaporator Coil: Located inside your home, this coil absorbs heat from the indoor air. As warm air passes over it, the refrigerant inside cools the air before it’s recirculated.
• Air Handler or Furnace: Works alongside the evaporator coil to move the cooled air through your ductwork and into each room.
• Condenser Coil and Compressor (Outdoor Unit): This part of the system sits outside your home. The compressor pumps refrigerant through the system, and the condenser coil releases the collected heat into the outdoor air.
• Refrigerant Lines: These insulated copper tubes connect the indoor and outdoor units, carrying refrigerant between them to complete the cooling cycle.
• Ductwork and Vents: These deliver cooled air throughout the home and return warm air to be cooled again. Properly sealed and insulated ducts are essential for system efficiency.

If any of these components are failing or underperforming, your system can suffer. This means your airflow, cooling power, and energy efficiency can all be affected. In other words, it may be time to consider a repair (or a full central AC replacement) — especially if your system is older or struggling to keep up.

Is It Time to Replace Your Central AC?

Older air conditioners (especially those over 10–15 years old) often struggle to keep up with the cooling demands of homes.
This is even more prevalent in places like Pomaria, Columbia, or Lexington, thanks to their hot, humid summers.

Here are some common signs it’s time to consider replacement:

• Frequent Repairs: If your AC is always breaking down, it’s more cost-effective to replace.
• High Utility Bills: Inefficient systems consume more energy and drive up cooling costs.
• Inconsistent Temperatures: Uneven cooling may be due to failing parts or outdated design.
• Outdated Refrigerant: Older systems using R-22 are obsolete and expensive to service.

Not sure if your system’s performing at its best? We’ve got you covered. Schedule a professional inspection with Wilson’s to get clear answers and expert recommendations.

Central AC vs Mini Splits: Which Is Better?

While central AC is ideal for whole-home comfort with existing ductwork, mini split systems are a growing favorite for homes without ducts or for zoned temperature control.

Both central AC systems and mini splits have their advantages, and the best choice depends on your home’s layout and your cooling needs. Central AC is ideal for whole-home cooling, especially if your home already has ductwork. It offers a clean, discreet look with vents rather than wall-mounted units, and it’s often more cost-effective for larger spaces.

On the other hand, mini split systems are ductless and provide excellent zone control. They’re perfect for additions, individual rooms, or homes without existing ductwork. While the upfront cost for mini splits can be higher per unit, they offer flexibility and efficiency in targeted areas.

If you’re unsure which system is right for you, our team at Wilson’s can help you compare options based on your home and budget.

Scheduling Central AC Installation or Replacement in Columbia, SC

At Wilson’s Refrigeration & Air, we understand the unique cooling needs of homeowners in Columbia, Pomaria, and surrounding areas of the Midlands. Whether you’re replacing a worn-out unit or installing central air for the first time, our experienced technicians will help you choose the most efficient, budget-friendly system for your space.

Ready for reliable comfort? Get in touch with Wilson’s today to schedule your central AC installation or replacement.