Your Complete Guide to Central Air Conditioning Systems

Choosing a new central air conditioning system is a major decision for your home and budget. It’s easy to get lost in a sea of technical terms, model numbers, and conflicting advice. You’re not just buying an appliance; you’re investing in years of comfort, energy efficiency, and peace of mind.

But how do you make a confident choice? How do you know which system is truly right for your home, your climate, and your wallet?

This guide is designed to be your trusted resource. We’ll skip the jargon and give you a clear framework for understanding your options. We’ll break down the different types of systems, explain what each component does, and reveal the one number you absolutely need to know before you buy. By the end, you’ll feel empowered to have an informed conversation with any HVAC professional.

The 3 Main Types of Central AC Systems

At a high level, central air conditioners fall into a few main categories. While there are variations, most homes in the Lake Stevens area will use one of these three systems.

System Type How It Works Best For

Split System The most common type, with components split between an outdoor unit and an indoor unit. Homes with existing ductwork and space for both indoor and outdoor components.

Packaged Unit All components (compressor, condenser, evaporator) are housed in a single cabinet outdoors. Homes with limited indoor space, like those without a basement or crawlspace.

Heat Pump A type of split system that can both cool your home in the summer and heat it in the winter. Homeowners looking for an all-in-one, highly efficient heating and cooling solution.

Deep Dive: The Split System AC

When you picture a central air conditioner, you’re probably thinking of a split system. In fact, they are the most common type of central AC in the U.S., accounting for the vast majority of residential installations.

A split system gets its name because it’s "split" into two main units: an outdoor metal cabinet and an indoor cabinet.

The Outdoor Unit: This houses the compressor and the condenser coil. It's the part of the system that does the noisy work and releases the collected heat from your home into the outside air.
The Indoor Unit: This contains the evaporator coil and a blower. It’s typically located in a basement, attic, or closet and is responsible for cooling the air and circulating it through your home's ductwork.

Pros of a Split System:

Higher Efficiency: Because the components can be larger, split systems often achieve higher energy efficiency ratings.
Quiet Operation: The compressor, the loudest component, is located outside, keeping your home quieter.
Flexibility: Components can be mixed and matched to create a customized solution for your home's specific needs.

Cons of a Split System:

Space Requirements: You need adequate space both inside and outside your home to house the units.
Complex Installation: Installation requires a qualified technician to connect refrigerant lines between the two units, a process that requires precision and expertise.

Deep Dive: The Packaged Unit AC

A packaged unit is an all-in-one solution. The compressor, condenser, and evaporator are all located in a single cabinet that sits outside, usually on a concrete slab in the backyard or on the roof.

Air ducts run from the outside unit into the house to distribute the cool air and return the warm air for conditioning.

Pros of a Packaged Unit:

Space-Saving: Ideal for homes with limited indoor space, as there’s no need for a large indoor cabinet.
Easier Installation: Since the components are pre-packaged at the factory, installation is often simpler and faster than for a split system.
Great for Commercial Buildings: Their rooftop placement makes them a popular choice for light commercial applications.

Cons of a Packaged Unit:

Exposure to Elements: All critical components are housed outdoors, leaving them more exposed to weather, debris, and potential damage.
Efficiency Limits: They tend to be slightly less energy-efficient than the highest performing split systems.
May Require a Crane: For rooftop installations, a crane is needed, which can add to the cost of a new professional HVAC installation.

The Ultimate Comparison: Which AC System Is Right for You?

Choosing between these systems depends on your home’s layout, your budget, and your efficiency goals. This matrix breaks down the key decision factors.

Decision Factor Split System Packaged Unit Heat Pump

Installation Cost Moderate to High Moderate High (but replaces furnace)

Energy Efficiency (SEER2) Good to Excellent (14-22+) Good (13-17) Excellent (14-22+)

Lifespan 15-20 years 10-15 years 15 years (used year-round)

Space Requirements Requires indoor & outdoor space Outdoor space only Requires indoor & outdoor space

Noise Level Quieter inside Louder (all components outside) Quieter inside

Best for WA Climate? Excellent for cooling Good for cooling Excellent for both heating & cooling

What's Inside? Understanding the 4 Core Components

Regardless of the system type, four crucial components work together in a continuous cycle to cool your home. Understanding their roles helps you appreciate how the system functions and why regular maintenance is so vital.

The Compressor (The Heart): Located in the outdoor unit, the compressor is the engine of the system. It pressurizes the refrigerant gas, raising its temperature significantly. This is the first step in moving heat from inside your house to the outside. If the compressor fails, you'll need an expert diagnosis and repair.‍
The Condenser Coil (The Heat Exchanger): Also in the outdoor unit, the hot, pressurized refrigerant flows through the condenser coil. A large fan pulls outside air across the coils, causing the heat to radiate away from the refrigerant. As it cools, the refrigerant turns from a gas back into a liquid.‍
The Evaporator Coil (The Chiller): Housed in the indoor unit, this is where the magic of cooling happens. The now-cool liquid refrigerant flows into the evaporator coil. As your home's warm air is blown across it, the refrigerant absorbs the heat, causing it to evaporate back into a gas. This process chills the coil, and the air blown over it becomes cold.‍
The Blower & Ductwork (The Lungs): The blower, or air handler, is the fan inside your indoor unit. It pulls warm air from your home through return vents, pushes it across the cold evaporator coil, and then sends the newly cooled air through the ductwork to be distributed throughout your house. This is also where air filters are located, which are critical for maintaining good indoor air quality.

The Most Important Number You've Never Heard Of: SEER2 Explained

For years, the standard for measuring AC efficiency was SEER (Seasonal Energy Efficiency Ratio). But as of January 1, 2023, the Department of Energy implemented a new, more rigorous standard: SEER2.

Think of it like the difference between a car's highway MPG and its city MPG. The old SEER rating was like a lab-tested highway MPG good, but not fully representative of real-world conditions. SEER2 testing uses conditions that more accurately reflect the static pressure your system will face in an actual home with ductwork. This gives you a much more realistic idea of how efficient the unit will be once it's installed.

Why does this matter to you?

It’s the Law: All new systems manufactured and sold today must meet SEER2 standards.
It’s a Better Benchmark: Comparing SEER2 ratings gives you a truer apples-to-apples comparison of system efficiency.
It Saves You Money: The Department of Energy states that replacing an AC unit over 10 years old with a modern high-efficiency model can cut your cooling costs by 20-40%.

In Washington and the Northern region of the U.S., all new split-system central air conditioners must have a minimum rating of 13.4 SEER2.

Future-Proof Your Comfort: Emerging AC Trends

AC technology is constantly evolving. A modern system does more than just cool your air; it offers unprecedented efficiency and control.

Inverter Technology: Traditional AC compressors are either on or off like a light switch. Inverter-driven compressors can operate at variable speeds, like a dimmer switch. They run at the precise speed needed to maintain the temperature, rather than constantly shutting on and off. According to the International Energy Agency, this can increase efficiency by up to 30%.
Smart Thermostats: Modern thermostats learn your habits, adjust for humidity, and can be controlled from your phone, giving you total command over your comfort and energy use.

Your 3-Step Action Plan to the Perfect AC

Navigating this decision is much simpler when you have a clear plan.

Assess Your Home: Do you have existing ductwork? Do you have space for an indoor unit in a basement or attic? Answering these questions will immediately point you toward either a split system or a packaged unit.
Use Our Matrix: Look at the comparison matrix above to weigh the factors that matter most to you upfront cost, long-term energy savings, or all-in-one heating and cooling.
Consult a Qualified Professional: The final step is to have a trusted technician perform a "load calculation" on your home. This professional analysis determines the exact size and power your system needs to cool your space efficiently without wasting energy.

Choosing the right central air conditioning system is a long-term investment. By understanding the core types, components, and the new SEER2 efficiency standard, you're now equipped to make a smart, confident decision for your home.

If you're ready to take the next step, our team at Good Guys is here to provide a no pressure HVAC consultation and custom solution tailored to your home in Lake Stevens. We believe in getting it right the first time, ensuring your comfort for years to come.