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Running an air conditioner certainly doesn’t require knowledge of how to build or even repair one, but learning how some of the main components work may help you better maintain your system. Here we explain about the air conditioner evaporator coil and air conditioner condenser coil.
Unlike a furnace that produces heat, an air conditioner relies on refrigerant or coolant to remove heat from the air by absorbing it and releasing it outside. The evaporator coil and the condenser coil are integral parts of this process.
The cooling process begins with the evaporator coil, also known as an evaporator core. It is located inside your home near the air handler (the blower fan) and consists of U-shaped tubes set into panels. The evaporator coil holds the refrigerant and is made of copper, steel or aluminum – materials that easily conduct heat. The panels are positioned to form an “A” and are lined with thin pieces of metal called “fins” which draw the hot air close to the refrigerant to maximize cooling.
The compressor pulls the liquid refrigerant through an expansion valve that relieves the pressure from the refrigerant and quickly cools it, allowing it to absorb heat as it then flows through the tubing in the evaporator coil. The valve controls how much refrigerant flows to the evaporator for overall energy efficiency. The blower fan draws the hot air over the evaporator coil. The refrigerant absorbs the heat, warms and evaporates.
When the water vapor in the warm household air hits the cold evaporator coils, the water vapor condenses into liquid form and drips down into the condensate pan, which drains the water away outdoors. This is how your evaporator coil reduces the humidity in your home.
In order to operate efficiently, the evaporator must be clean. Dust can prevent the refrigerant from properly doing its job and cause the system to work harder than necessary to cool your home. Keeping the evaporator free from dust and debris requires regularly changing or cleaning the air filter (every 30-90 days) and scheduling annual maintenance by a certified HVAC technician to thoroughly clean and inspect the system.
Frost on the evaporator coil indicates that the system is dirty and malfunctioning in some way. Do not run an air conditioner if you notice frost because doing so can cause serious damage to the equipment. Evaporator coils can also develop tiny pinhole leaks due to corrosion caused by moisture from condensation mixing with common household chemicals in the air. Oily residue around the evaporator or in the drain pan is a sign your coil is leaky and requires replacement. The chemicals in the air are called volatile organic compounds (VOCs) and come from carpeting, fabrics, cleaners, pressed wood, air fresheners and other similar sources. Maintaining proper ventilation can prevent VOCs from harming your air conditionaer and your health.
The condenser coil is housed in the condenser unit, the portion of the air conditioner system that is outside and houses the compressor, the condenser coil and a fan.
After the refrigerant in the evaporator coil has absorbed the heat from the air in your home, a copper tube transfers it to the condenser unit. The low-pressure, warm refrigerant gas enters the compressor where it is pressurized and turns into a hot, high-pressure gas. From there, the gas flows into the condenser coils and the refrigerant releases most of the heat it has absorbed. The fan on the top of the condenser unit also causes the refrigerant to lose heat by blowing air over the condenser coil. The condenser coil is designed to maximize the time the refrigerant is in contact with the blowing air, so it can release as much heat as possible.
As it cools, the refrigerant changes from a hot gas to a hot liquid. From there, it flows back through a copper tube into your home and into the expansion valve located in the indoor unit near the evaporator coil.
Similar to the evaporator coil, the condenser coil needs to stay clean. To ensure proper airflow, periodically check for debris, such as leaves and branches, that may be blocking the system. Maintain a clear area around the unit and prevent leaves or other foliage from falling on or near the condenser. Frost or even ice can develop on the condenser unit as a result of dirt in the system. If you notice a buildup of dirt on the condenser coil, use a stiff brush to gently clean the fins. Annual professional maintenance will keep the condenser coil, and the entire condenser unit in good shape.
It’s important to perform routine A/C maintenance that keeps your evaporator and condenser coils and the rest of your system running efficiently. If something does go wrong, you’ll be better able to troubleshoot the problem. Your knowledge will also help you make smart choices when you’re ready to buy replacement components or upgrade your air conditioner.