Keeping Summer Cool — How Does Central Air Work?

Feeling a blast of cold air on your skin after feeling the burn of sweltering heat outside is a common summer experience. Learn the why and how of A/C to keep cool.

how central air works

Indoor unit

Typically, the indoor unit of your central air conditioning system is located in the attic, a closet or the basement. This unit contains an evaporator made up of copper coils through which the system’s refrigerant (cooling fluid) flows.

Remember how that cold glass of water acted as a sponge, absorbing heat from the outside air? That’s exactly how the evaporator works. As refrigerant moves through the copper coils of the evaporator, it vaporizes as it absorbs heat from the inside of your house, leaving cool air behind. This cool air is pumped back into your house, and the system pumps the heated, vaporized refrigerant to the outside unit.

Outdoor unit

The outdoor unit of your central air conditioning system, usually located at the side or back of your house, contains the compressor, condenser coil, a fan and various electrical components.

The heated refrigerant vapor from inside your house moves through the compressor, which heats the refrigerant to an even higher temperature. The higher the temperature of the refrigerant, the faster heat is transferred to outdoor air. The highly pressurized and heated refrigerant moves to the condenser coil, and a fan blows air over it, cooling the coil, and the heat from inside your house disperses into the atmosphere.

As the refrigerant in the condenser coil cools, it returns to its original liquid form and is pumped back into your house as the cycle repeats itself.

The refrigeration cycle summarized

When the temperature in your house rises above the temperature you’ve programmed into the thermostat, the thermostat turns on the central air conditioning system.

A fan in the system draws warm air from the rooms of your house to the evaporator in the inside unit. The liquid refrigerant is pumped from the outside unit to the evaporator, where the refrigerant vaporizes as it absorbs and removes the heat pumped from the rooms of your house.

The cooled air is pumped back into your house, and the heated, vaporized refrigerant moves heat to the outside unit for dispersal into the atmosphere.

Maintenance and warranties

Modern central air conditioning systems are highly reliable, and taking just a few home maintenance steps, such as replacing your air filter when needed and closing air vents in rooms you rarely use, can help keep them functioning normally. As with any mechanical system, however, problems that require the services of a professional will eventually arise.

Consider purchasing an American Home Shield Warranty to help protect yourself from those expensive repair costs. Call us today at (866) 223-7938 or contact us online for a free, no-obligation estimate on the American Home Shield plan that’s best for you.



AHS assumes no responsibility, and specifically disclaims all liability, for your use of any and all information contained herein.

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New Jersey Residents: The product being offered is a service contract and is separate and distinct from any product or service warranty which may be provided by the home builder or manufacturer.