When it comes to staying cool in the summertime, your home air conditioning system is essential. Most homeowners know to switch out their filter every three months and have regular annual maintenance performed on their system. However, beyond these preventative maintenance tasks, many homeowners don’t actually understand how their centralized air conditioner works. Fortunately, we’re going to discuss it in detail below.


Every air conditioning system has a thermostat that is essentially the brains of the entire unit. When you switch your thermostat to the cooling function, you need to set the desired temperature for your home. Your thermostat will display the actual temperature inside your home. If the actual temperature is above your set desired temperature, the thermostat will signal to the rest of the air conditioning components that they need to turn on.

Air Handler and Filtering

Throughout your entire home, there is a series of ductwork. This consists of large metal piping attached to vents throughout each room in your home. Half of the vents in your home will be for supplying cold air. The remaining half of the vents will be for returning warm air to your air conditioning system. When your thermostat signals to the air conditioning unit to kick on, air is pulled in for the return ductwork via the air handler. In a split-system home, the air handler that is used to pull in the warm air is also utilized in the furnace during the winter months of the year.

As the air gets pulled into the ductwork, it will go through the air filter. There are a few different types of filters that your system can have, each offering its own level of particle filtering. Your filter will help remove unwanted allergens, pollutants, and other airborne debris from the air inside of your home. If you have an air purifier installed, this will also work to filter the air to make it cleaner for your family to breathe. Most centralized air conditioning systems do not come standard with an air purifier. Rather, you’d have to purchase one as an addition to your system.

Refrigerant and Evaporator Coil

After the hot indoor air passes through the air filter and potentially the air purifier, it makes its way over the evaporator coil. This evaporator coil is utilized to transfer the heat from the air to the refrigerant inside the coil. As the heat transfer process happens, some of the moisture from the humid air is extracted into liquid form. The excess water drains down into the drain pan of your indoor air conditioning unit.

The refrigerant that enters the evaporator coil is initially in a liquid form. As it bonds with the heat from the air that passes over the evaporator coil, it turns into a gas form. This gas form makes its way to your outdoor compressor unit via copper tubing. The air that traveled over the evaporator coil is now cold because it had the heat removed from it. This cold air is forced through the supply ductwork in your home to deliver cold air to each room via the supply vent.

Condenser Coil

As the outdoor compressor unit pumps the heated gas refrigerant outside, the refrigerant enters the condenser coil. At the same time, a fan in the outdoor unit pulls fresh air over the condenser coil. This fresh outdoor air removes the heat out of the gas refrigerant. This is another heat transfer process where the end result is that the heated air is blown back outdoors. As the heat is removed from the refrigerant, it starts to turn back into its liquid state.

Expansion Valve

Once the heat is removed from the refrigerant, it is piped back inside via the copper tubing. Before it can return to the evaporator coil, it has to go through an expansion valve. This valve has two main jobs to do. First, it helps change the pressure of the refrigerant so that it will be able to turn back into a gaseous state after bonding with heat again. Second, it regulates how much refrigerant can go into the evaporator coil at one time. Once the refrigerant enters back into the evaporator coil, the whole heat transfer process starts all over again.

It’s All About Heat Transfer

As you’ve learned how the air conditioning process works, it should become very clear that it’s essentially a heat transfer process. Heat is transferred from the air inside of your home to the refrigerant inside of the evaporator coil. That refrigerant is placed outside, and the heat is transferred from it to the air outside. In retrospect, heat is transferred from the air inside of your home, and it ends up outdoors.

Split Systems Versus Other Units

The entire air conditioning process that we just covered describes a homeowner who has a split system air conditioner. Split systems are the most popular type of home air conditioning system out there. One of the easiest ways to identify a split system is that it has both an indoor unit and an outdoor unit. There are two other types of air conditioning systems that a house may have in it. These include packaged systems and ductless mini-split systems.

Packaged air conditioning systems work much in the same way that the split system works. However, the main difference is the packaged system has all the air conditioning components, including the evaporator coil and the condenser coil, in the outdoor unit. There is no indoor unit with a packaged air conditioning system. This makes it perfect for homes that don’t have a whole lot of extra space to house an indoor unit.

The other type of air conditioning system that may be purchased for a home is a ductless mini-split system. Unlike split system air conditioning units, ductless mini-split units have one main compressor outside and a series of individual wall-mounted units. The wall-mounted units are connected to the outdoor compressor unit via copper tubing. Ductless mini-split systems are highly recommended for homes that do not have any existing ductwork in the walls and for any additions that cannot connect to the existing ductwork that is run throughout a house.

Tips for Energy Savings

Running your air conditioning system throughout the summer months can get quite costly. Having some tricks up your sleeve to help reduce your energy consumption is a great way to ensure that you get to keep more of your money in your bank account. One of the best methods that you can utilize to help reduce your energy cost is to use the exhaust fans inside of your home. Most homeowners have an exhaust fan in the bathroom and above the stove.

These exhaust fans are designed to remove humid air from inside your home. This is essential because a humid indoor environment can make you feel a lot hotter than you actually are. In fact, humidity can make your family feel like your home is 10 degrees warmer than it actually is on the thermostat. When you feel hotter than the indoor environment, you turn your thermostat down even more. This requires your air conditioning system to continue to run and consume more energy.

Another great way to make your family feel like it’s colder than it actually is inside of your home is to invest in ceiling fans. They should be placed in bedrooms, home offices, living rooms, and kitchens. Having the fan blades in a counterclockwise direction will force the air down onto you. When the air is blowing across your skin, it can make your home environment feel up to 8 degrees colder than it actually is.

Trustworthy AC Service

When it comes to relying on a local Harrisburg air conditioning servicer, no look further than HB Home Service Team. We provide heating, cooling, plumbing, oil, and propane services for the entire region. Simply give us a call today!

HB Home Service Team

company icon