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Air Conditioner

Inside the Split AC System

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Most central AC systems are referred to as split systems. Why? They consist of two distinct units or subsystems that are physically separated (split) but designed to work as an integrated whole.

With that in mind, let’s look at the basic units, what they do and how they work together to create the cooling effect we crave when the temperatures soar.

Outdoor Unit

The outdoor unit contains the hot, noisier system components that many HVAC experts describe as the heart of the air conditioning process. It holds the compressor, the component that functions like a pump to pressurize (compress) the refrigerant. Pressurization converts the refrigerant from a low pressure gas to a high pressure gas, a process that generates significant heat.

The compressor moves hot refrigerant into the condenser coil, which consists of a network of copper or aluminum tubes. As the refrigerant circulates, the coil absorbs and discharges heat, which cools the refrigerant and allows it to convert or condense into a liquid.  The condenser fan contributes to this process by blowing heat out of the unit into the surrounding air where it can dissipate.

As heat is dispersed, the refrigerant leaves the outdoor unit and heads toward the indoor unit, traveling through a connecting tube or pipe.

Indoor Unit

The indoor unit contains the cooling components and air handling and distribution equipment. As the refrigerant travels indoors, it loses pressure and grows cooler. It passes through an expansion valve that controls the volume of refrigerant that enters the evaporator coils, the network of cold, low-pressure tubes typically located in or attached to the furnace.

At this point, several critical things happen. The air handler or blower (usually located in the furnace) draws warm air from the return ducts and blows it across refrigerant-filled evaporator coils. The refrigerant absorbs heat from the air, and when it reaches its boiling point, it converts to vapor, absorbs even more heat and creates the cooling effect we desire.

Once the air is cooled, the air handler blows it into the distribution ducts so it can be channeled throughout your home. At the same time, the refrigerant continues to collect heat from the air, which contributes to the cooling effect and keeps it in a gaseous state.

The Cycle Continues

The refrigerant travels back to the condenser and the whole process is repeated until indoor temperatures are sufficiently cool and the thermostat shuts off the system.

The split AC system is a marvelous mix of hot outdoor components and cool indoor components that work in concert to deliver that miracle of modern technology: an oasis of crisp, cool air during the hot, humid days of summer.

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