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How Does an Air Conditioner Cool Your Home?

Cincinnati area home and business owners rely on air conditioners to keep indoor conditions cool and comfortable throughout the summer. Are you aware of how air conditioners work to do this important job, day after day?

Thomas & Galbraith’s air conditioning specialists help demystify your cooling system as we share the details of the air conditioning process. Learn about available air conditioning system types, key components, and how to best care for them. We’re here to help you make the most out of your air conditioner’s performance and efficiency – contact us today for help!

How Air Conditioners Work: Key System Components

To best understand how air conditioners work, you need to know the components that complete the process. Air conditioners are made up of many parts that each have a job to do – it’s a long list. There are a few key components you need to know about to understand the cooling process.

  • Condenser coil: Sometimes referred to as the outdoor coil (because it sits in the outdoor unit), the condenser coil is the component that lets off heat into the outdoor air.

  • Compressor: The compressor is a type of pump for refrigerant inside the air conditioner. The compressor not only moves refrigerant throughout the cooling system but also pressurizes it.
  • Evaporator coil: Also called an indoor coil (because it is located within the system’s indoor components), the evaporator coil’s job is to extract heat from the air inside your home.

Each of these air conditioning system components uses the refrigerant to complete its part in the cooling cycle. The components are linked by the system’s refrigerant lines, through which refrigerant cycles. Depending on the stage of the cooling cycle, refrigerant is either in a liquid form or is a vapor.

If you purchase a new air conditioner, your system uses a refrigerant called Puron or R-410A. This is a newer hydrofluorocarbon (HFC) that is more environmentally friendly and does not produce emissions that damage the ozone layer. Older systems use Freon, or R-22 refrigerant, which is a hydrochlorofluorocarbon (HCFC) that is known to contribute to ozone layer damage. R-22 is currently part of a worldwide phaseout – no new air conditioners are manufactured to use Freon.

How Air Conditioners Work: Steps to the Cooling Cycle

How air conditioners work is not how many people think. Furnaces create heat that warms the air – many assume air conditioners work in a similar manner by creating cooling that is infused into the air. In reality, how air conditioners work is just like the refrigerator that stores your food. It cools when it pulls excess heat out of the air inside. The excess heat is expelled from your home, and the result is cooler air inside.

Here’s a look at the steps in the cooling cycle for a more in-depth look at how air conditioners work:

  1. Air from inside your home circulates through the return ducts and into the indoor cooling system cabinet that holds the evaporator coil.

  2. Hot air passes over the evaporator coil, which contains refrigerant in a liquid state that absorbs heat in the air. The evaporator coil absorbs heat, which produces condensation and removes humidity from the air.

  3. Refrigerant is converted from liquid to gaseous vapor and travels through the refrigerant lines to the compressor outdoors. The compressor compresses the refrigerant, which ups the pressure and temperature.

  4. The refrigerant then passes to the condenser coil in the outdoor unit. Here, heat is let off from the coil. It passes into the environment as it circulates through the chamber and out the fins that wrap around the exterior of the unit. Refrigerant drops in temperature and pressure as it converts to a liquid.

  5. The refrigerant is ready to continue the cooling process and repeat the cycle until the home reaches the temperature set on the thermostat. The air conditioner’s expansion valve regulates the flow of refrigerant. The expansion valve sends newly cooled liquid refrigerant back to the evaporator coil.

This process of how air conditioners work repeats according to the settings on your thermostat inside. The air conditioner continues to run through the cooling cycle until the air inside your home or workplace reaches the temperature set by the thermostat. The thermostat is a control that tells your air conditioner how long to run. It shuts down the air conditioner once the set temperature is achieved and fires it up again when the temperature rises.

Types of Air Conditioning Systems in Cincinnati

There are several air conditioning equipment options available for installation in Cincinnati homes and businesses. No matter which type you choose, how air conditioners work is the same from type to type. Their differences arise from configuration and features.

Central Air Conditioning

How air conditioners work in a central cooling system is through a network of ducting. Cooled air circulates from the air conditioner through the ducts and into your home through the duct system’s vents.

Central air conditioning systems are configured as split systems or packaged systems. In a central AC system, there is an indoor unit that houses the evaporator coil. There is also an outdoor unit that houses the condenser and compressor. In a packaged system, all components are contained in the same cabinet, which is typically installed on the roof or on the ground at the exterior of the home or building.

Ductless Air Conditioning

Ductless systems do not use ducts for how air conditioners work. These systems consist of an air conditioner or heat pump located outside, which is connected to individual air handlers installed indoors. A single ductless system is able to support multiple air handlers. Air handlers deliver conditioned air directly into the space they serve, which creates a zoned cooling system for the home.

Heat Pumps

How air conditioners work and how heat pumps work is the same, except a heat pump is able to reverse its process to heat as well. Heat is pulled from and let off into either the air outdoors or underground depending on the type. Air source heat pumps use the air outside as a heat source and receptacle to give off heat, while geothermal systems use a below-ground network of pipes to absorb and expel heat.

Maintenance for Your Cincinnati Air Conditioner 

When you know how air conditioners work, you have a better understanding of what they need to complete the cooling process. As a Cincinnati home or business owner, there are some key tasks you need to do on a regular basis to protect this important piece of equipment.

The cooling process wouldn’t be possible without good airflow through the system, which is critical to how air conditioners work. Here are the steps to take to ensure your air conditioner has proper airflow at all times:


  • Check your interior air conditioning system cabinet (or individual air handlers for ductless air conditioners) regularly and ensure there are no items stored up against them. Items stored in the surrounding area have the potential to block airflow to the unit.

  • Inspect all floor, ceiling, and wall vents to make sure all are open. Also, they must not be blocked – remove all furniture, rugs, and other items that are in the way.

  • Change your furnace filter on a regular basis. Your air conditioner uses the same filter your furnace or heat pump does in the wintertime. The filter is important in how air conditioners work as it lets air flow through the system – as a bonus, it also pulls airborne contaminants from the air supply. Change furnace filters per the filter manufacturer’s recommendations, which range from one month to 12 months (lower quality filters need to be changed more frequently than higher quality filters).

  • Check furnace filters monthly. In the summer, how air conditioners work is almost on a constant basis. When they work more, filters are depleted faster than in the spring or fall. It’s smart to pull your filter out and examine it once per month. If it’s gray and loaded with contaminants, it needs a change even if you have not reached the recommended interval.


  • Clear away debris from exterior air conditioning components. Grass clippings, dirt, leaves, branches, and more get stuck to the unit’s exterior, which has the potential to block airflow. Gently clear this debris away and do so on a regular basis to prevent buildup.

  • Remove vegetation that grows up around the outside unit. Prune shrubs and trees that grow close by to prevent them from affecting the unit.

  • Leave two feet of clearance surrounding the exterior unit. This allows enough room for air to flow to the unit. It also provides space for a technician to reach the equipment for repairs and maintenance.

  • Never store items against the outdoor air conditioning unit. Lawn furniture, outdoor storage cabinets, and other items should be stored elsewhere to avoid airflow blockages.

Preventative Maintenance for Cincinnati Air Conditioners 

Preventative maintenance is one of the best ways to protect your Cincinnati air conditioner. Preventative maintenance is like a tune-up for your air conditioning system – it delivers the care your system needs to negate wear and tear and improve performance. Better performance improves energy efficiency to help control cooling costs.

This is a task performed by an HVAC professional to protect how air conditioners work. Many maintenance tasks are performed to address system components, which ensures safe, proper function, and proper airflow through your air conditioner. Schedule preventative maintenance with Thomas & Galbraith each year – our Carefree Maintenance Agreements ensure your cooling system is serviced on a regular basis.

You now know how air conditioners work – make sure you get the best performance and energy efficiency from your cooling system with the right equipment and services from Thomas & Galbraith Heating, Cooling & Plumbing. Our skilled HVAC technicians offer quality air conditioning installation, repair, and maintenance to deliver ultimate indoor comfort throughout the Cincinnati summer! Contact us today for air conditioning help.

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