Understanding And Maintaining Your Central Air Conditioning System

Servicing your home's central air conditioner can prove to be a difficult task, especially if you don't understand how the system's components work together to cool the air inside of your home. Learning about your central air system can help when it comes time to do some repairs or routine maintenance. Below is a detailed list of the components that make up your central air system, as well as the steps needed to keep your system in working order.

Central Air Conditioning Components

Your home's central air system is comprised of four main components:

  • A compressor
    • The cooling process begins in the compressor, a metal box located outside of the home that is full of a gas called "refrigerant."
    • The compressor pressurizes the gas, increasing its temperature.
    • Once the gas is extremely hot, it is sent to the condenser.
  • A condenser
    • The condenser converts the hot gas into a cool liquid by quickly depressurizing the refrigerant.
    • This releases the heat contained in the gaseous refrigerant out into the open air.
    • This cold, liquid refrigerant is then sent into the home and into the evaporator.
  • An evaporator
    • The evaporator, located inside of the home, is comprised of dozens of hollow metal coils that are filled by the cold refrigerant.
    • A large fan blows air through these coils, pushing chilled air into the home's duct system.
    • As the liquid refrigerant leaves the evaporator, it travels through a small opening called the expansion valve.
  • An expansion valve
    • The liquid refrigerant is sent through the expansion valve, lowering the pressure of the liquid so quickly that it reverts back to a gas.
    • This process absorbs heat from the house before sending the refrigerant back into the compressor.

These components work together to achieve what is known as a "phase conversion." When the gaseous refrigerant is converted into a liquid, its latent heat is released into the outside air. Once inside the home, the liquid refrigerant is converted into a gas, absorbing the heat from the home before sending it outside.

This process is an everyday application of the scientific principle that heat is absorbed when a liquid is converted to a gas, and heat is expelled when a gas is converted into a liquid. As you can see, your central air system doesn't only blow cooled air into your home, but it actually pulls hot air out of the home as well. This is why central air units are so efficient and fast-acting.  

Maintaining This System

The most practical way to keep your central air system in working order is to regularly clean the evaporator coil. As you now know, the evaporator handles the chilled liquid refrigerant inside of the home. However, the evaporator's metal coils become covered with frost during operation, causing dirt, dust, and other airborne particles to stick to the coils.

To clean your evaporator, follow these steps:

  1. Access the evaporator.
    • The evaporator is always located directly above the furnace in your home.
    • Remove the metal surface that covers the evaporator with a screwdriver.
  2. Scrub the coils with a toothbrush.
    • Using a mixture of bleach and water, scrub the metal coils, removing any buildup that you can see.
  3. Clean the drain pan.
    • Pour a small amount of bleach into the drain pan to clean the drain tube at the middle of the pan. This stops any mold growth and ensures that the drain is not blocked.

Since you now know that all of the cooled air enters the home through the evaporator, you can see how cleaning the evaporator increases airflow and improves the quality of the air inside of the home. Optimal airflow reduces strain on the other components of the system, and keeps your home cool and comfortable during the hot summer months.

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