How Does an Air Conditioner Work?

Unless you’re an HVAC specialist, you probably don’t think about your central air conditioning system on a regular basis. However, w hen your air conditioner stops working and the temperature of your home is unbearable, AC is all you can think about. During these tim es of reflection as you wait for the HVAC repair service to arrive, you may ask yourself the question, “How does my air conditioner work i n the first place?” To answer that question, here is a simple explanation of the different components in your air conditioner and how they work togeth er to cool your home: Air Conditioner Basics Your air conditioner cools your home using a basic physical law: when a liquid converts to a gas, it absorbs heat. Your AC unit uses t his principle to take heat from the air in your home and send it outside. To do this, it uses various components, starting with refrigerants . Refrigerants Refrigerants are substances that are easy to convert between liquid and gaseous states. This allows them to absorb heat while they are in a cool liquid state, convert quickly to a gas to carry the heat outside, then cool back into a liquid to start the cycle over again. Refri gerants, like their name suggests, do most of the actual cooling in your AC system. Evaporator The air conditioning cycle begins inside your home in an apparatus called an evaporator. An evaporator consists of a series of metal coils that contain cool, liquid refrigerant. As the warm air in your home comes in contact with these coils, the liquid refrigerant in the coils absorbs the heat, causing the surrounding air to cool. To aid in this process, your AC system has a series of fans called blowers. These blowers move the warm air in your home over the e vaporator coils. This speeds up the heat transfer toward the refrigerant and spreads the cooled air into your home. As this process continues and the refrigerant continues to heat up, it vaporizes into a low-pressure gas. This change from liquid to g as causes the refrigerant to absorb the maximum amount of heat from the surrounding air. Then, because the refrigerant can’t absorb a dditional heat, it flows through a hose to the next component of the air conditioning cycle, called the compressor. Compressor A compressor, as per its name, takes in the heated gas from the evaporator and compresses it. This raises both the pressure and te mperature of the gaseous refrigerant. Because heat transfers from a hotter substance to a colder substance, the gaseous refrigerant mus t be hotter than the air outside to be able to dissipate the heat it collected from inside your home. After it is compressed, the hot, high-pressure refrigerant leaves your home through a tube to a device called a condenser. Condenser A condenser unit located outside of your home performs the exact opposite function of the evaporator in your home. It uses a serie s of coils, metal fins, and fans to dissipate heat away from the refrigerant and convert it back into liquid. The heat from the refrigerant st ays outside your home and the cooled refrigerant heads back toward the evaporator to begin the cycle again. Before it reaches the evap orator, however, it travels through an expansion valve. Expansion Valve An expansion valve is a device that regulates the flow of the cooled liquid refrigerant back into the evaporator coils. This helps the ev aporator maintain the correct level of refrigerant so that it can easily convert it into a gas again. Additional Air Conditioner Functions In addition to cooling your home, your AC system performs a few other important tasks to make the air in your home safer and mo re comfortable. Dehumidify Properties Interestingly, the design for the modern AC system was not invented as a means of cooling a building, but rather to remove excess humidity. As warm air passes over the evaporator, moisture condenses on the coils. This is the same effect you can observe on the outsi de of a cold glass of water on a humid day. This also explains why water tends to pool around your AC unit on a humid day. The result i n both cases is that it removes moisture from the air, leaving the room feeling more pleasant. Air Filtering Your AC system also includes a filter to remove pollutants and allergens from your home’s air. Most AC systems use a mechanical air filter located near the blowers to clean the air before it circulates it back into your home. Keep this information in mind next time you schedule a repair for your AC system. Now that you are well-versed in the basic parts of your air conditioning system, you can impress your HVAC repair person. More importantly, you will be able to understand which parts of your system he or she is fixing, what those parts do, and why it is important.