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AC Coils 101: Everything You Need to Know

This article was created in part with AI. Upon the initial draft, a human reviewed, edited, and revised the content to ensure accuracy.


Air conditioning coils are a crucial component of any HVAC system. These coils regulate the temperature and humidity in a home. By absorbing heat from the air inside and releasing it outside. AC coils are made up of thin tubes containing refrigerant. Which is a special fluid that can easily change between a gas and a liquid. The refrigerant absorbs heat from the air inside your home. And then releases it outside, helping to keep the air inside your home cool and comfortable.


AC coils can be found in an HVAC system's indoor and outdoor units. And play a vital role in maintaining a comfortable environment year-round.

This article will explore the different types of AC coils. Their materials. The signs to look for in a dirty AC coil and how to maintain and clean them properly.


Jump to Section:

  1. The Different Types of AC Coils

  2. Materials used in AC Coils

  3. The Importance of Regular AC Coil Cleaning and Maintenance

  4. How to Spot a Dirty or Malfunctioning AC Coil

  5. The Step-by-Step Process to Cleaning Your AC Coils

  6. Frequently asked questions

  7. Conclusion

The Different Types of AC Coils

The evaporator coil is found in the indoor unit of an HVAC system. It is a series of thin tubes containing a refrigerant. The refrigerant inside the evaporator coil is under low pressure. As the refrigerant absorbs heat from the air passing over the coil, it becomes a gas. The compressor in the outdoor unit of the HVAC system then compresses the gas. This releases the heat from the air and turns the refrigerant into a liquid. The liquid is then returned to the evaporator coil to repeat the process.


The condenser coil is found in an HVAC system's outdoor unit. It is also made up of a series of thin tubes containing refrigerant. The condenser coil is responsible for releasing the heat absorbed by the refrigerant in the evaporator coil. And dissipating it into the outside air.

The refrigerant inside the condenser coil is under high pressure when it enters the coil. As the refrigerant passes through the coil, it releases the heat absorbed from the indoor air and cools down. Turning it back into a liquid.


The coils in a heat pump work similarly to those in a regular AC system, with the addition of a reversing valve. The reversing valve in a heat pump allows the refrigerant flow to be reversed. So that the heat pump can be used for heating and cooling.

When the heat pump is used for heating, the reversing valve directs refrigerant flow through the evaporator coil in the indoor unit. Causing it to absorb heat from the outside air and release it inside the building. This means that the evaporator coil becomes the condenser coil. As it releases heat rather than absorbs it.

When the heat pump is being used for cooling, the reversing valve directs refrigerant flow through the condenser coil in the outdoor unit. Causing it to dissipate heat absorbed by the refrigerant into the outside air. This means that the condenser coil becomes the evaporator coil. Absorbing heat rather than releasing it.

In a packaged unit, the evaporator and the condenser coils are housed within the same unit. A packaged unit can either have gas heating with an AC system for cooling. Or be a heat pump that uses refrigerant for both heating and cooling.


Learn more about the types of HVAC systems.


Materials Used in AC Coils

Copper has been used in HVAC systems for many years, dating back to the early days of air conditioning. Copper is a highly conductive metal that can transfer heat efficiently. Making it an ideal material for use in AC coils. Copper is also durable and resistant to corrosion. Which makes it long-lasting and reliable. All of which made it a good choice for HVAC systems.

In the 1970s, aluminum began to be used as an alternative to copper in HVAC coils. Aluminum is a lightweight and corrosion-resistant metal that is less conductive than copper. But can still transfer heat effectively. Aluminum coils are also less expensive and easier to manufacture than copper coils. Making them a more cost-effective option for HVAC systems.

As aluminum coils became more popular in the HVAC industry, manufacturers began to develop aluminum alloy coils. These coils were even more effective at transferring heat. These aluminum alloy coils were made by combining aluminum with other materials. Such as copper, to create a more conductive and durable material. Aluminum alloy coils are now widely used in HVAC systems. This is due to their high heat transfer capabilities and low cost.

Today, copper and aluminum alloy coils are commonly used in HVAC systems. With the choice of material depends on the system's specific needs. Copper coils are generally more expensive but offer higher conductivity and durability. While aluminum alloy coils are a more cost-effective option. But still with good heat transfer capabilities.

Most residential HVAC equipment manufacturers use an aluminum alloy. And when you are looking to buy a system. And are concerned about energy efficiency. It is the energy efficiency rating that matters.


The Importance of Regular AC Coil Cleaning and Maintenance

Regular AC coil cleaning and maintenance cannot be overstated. AC coils play a vital role in the operation of an HVAC system. And keeping them clean is essential. For the efficient and effective operation of the system.

Two of the main reasons to clean and maintain AC coils are to improve the energy efficiency of the HVAC system. And to improve the IAQ (indoor air quality) in the home. When the coils are dirty or clogged with debris, they are less able to transfer heat. Which can cause the system to work harder and use more energy. And dust or mildew build-up on the indoor coil can transfer into the home. Regular cleaning and maintenance can help keep the coils and IAQ clean. And improve the system's overall efficiency.

Inspecting the coil for signs of leaks is an important aspect of AC coil maintenance. Leaks can occur in the coils due to damage, corrosion, or other factors. And it is important to identify and repair any leaks as soon as possible. One sign of a leak is a bluish-green stain on the copper refrigerant lines. Which is caused by the copper reacting with the refrigerant.

There are a few key tips to follow when maintaining AC coils. One is to wash the outdoor coils with water regularly. As this can help remove the accumulated dirt and debris on the coils. And another tip is to keep up with air filter changes. Dirty filters can contribute to dust and debris build-up on the indoor coil. By following these tips, you can help to keep your AC coils clean and well-maintained. Which will improve the efficiency and effectiveness of your HVAC system.


Learn more about cleaning the AC coils below.

How to Spot a Dirty or Malfunctioning AC Coil

Several signs may indicate a dirty or malfunctioning AC coil. Below, we talk about some of the most common signs of a dirty or malfunctioning AC coil.

If the static pressure in the HVAC system is higher than normal, it could be a sign that the AC coils are dirty or clogged. This can cause the system to work harder and use more energy as it forces air through the system.

If the blower motor makes unusual noises on the indoor unit, it could be a sign that the AC coils are clogged or dirty. The motor may be struggling to move air through the dirty coils, which can cause it to make unusual noises.

A noisy compressor motor on the outdoor unit can signal that the evaporator coil is dirty. The compressor is an important component of an HVAC system. It compresses and circulates the refrigerant through the system. When the compressor is functioning properly, it should run smoothly and quietly.


If the evaporator coil is dirty, it can cause the compressor to work harder. This increased workload can cause the compressor to make unusual noises. Such as humming, buzzing, or knocking.

Learn more about the refrigeration cycle here.

Dirty AC coils can cause a refrigerant leak in an HVAC system. When the coils are dirty or clogged, they are less able to transfer heat. And cause the refrigerants to work at higher pressures. This increased workload can put extra stress on the refrigerant lines and connections. If a connection becomes too weak, it can cause a leak in the system.

If visually accessible, a sign of a leak is a bluish-green stain on the copper lines or oil spots on the coils.


Higher temperatures from the air vents can signify a dirty outdoor condenser coil. The condenser coil is responsible for releasing heat to the outside air. And is located outside. When the condenser coil is dirty or clogged, it can reduce the ability of the system to release heat. Not allowing the refrigerant to supercool properly. When the refrigerant doesn't supercool enough, it can cause the air coming out of the vents to be warmer than normal.

You can spot a dirty air conditioning coil by paying attention to these signs. And take steps to clean or repair it as needed. This will help to maintain the efficiency and effectiveness of the HVAC system.

The Step-by-Step Process to Cleaning Your AC Coils

The process of cleaning the outdoor condenser coil in an HVAC system involves the following steps:

  1. Turn off the power to the unit: Before cleaning the condenser coil, it is important to disconnect the power to the HVAC unit. This will help to prevent any accidental electrical shocks or injuries.

  2. Remove any debris: Before cleaning the condenser coil, remove any debris on or around the coil. This may include leaves, twigs, or other debris accumulated on or around the unit.

  3. Remove the condenser fan: To access the condenser coil, you may need to remove the fan. This is done by loosening the screws or bolts that hold the fan in place and carefully lifting it off. Be careful when handling the fan, as it may be heavy and cause injury if dropped.

  4. Remove the protective panels: Before you start cleaning the coil, you will need to remove the protective panels. These panels are secured with screws or bolts. And can be removed by loosening them and lifting the panels off.

  5. Clean the fins: The condenser coil is made up of thin metal fins that are designed to help transfer heat. You can use a soft brush or a can of compressed air to clean the fins. Be gentle when cleaning the fins, as they are delicate and can be damaged.

  6. Rinse the coil: Once you have cleaned the fins, you can rinse the coil with water. You should not use a strong stream of water, as this could damage the fins. Instead, use a gentle stream of water and wash the coils from the inside out. Rinse the coil thoroughly to remove any dirt or debris that may be stuck to the surface.

  7. Clean the surrounding area: After cleaning the condenser coil, it is important to clean the surrounding area. This may include removing any weeds or grass that has grown up around the unit. And cleaning any debris or dirt that may have accumulated on the ground.

It is important to note that you should not use cleaning detergents, chemicals, or abrasive materials. Only use materials approved by the equipment manufacturer. The wrong substances can damage the fins and reduce the unit's efficiency.


The process of cleaning an indoor evaporator coil in an HVAC system typically involves the following steps:

  1. Turn off the power to the unit: Before you start cleaning the evaporator coil, it is important to turn off the power. This will help to prevent any accidental electrical shocks or injuries.

  2. Access the evaporator coil: The evaporator coil is typically located in a hard-to-reach place. Such as inside the air handler or furnace, which can be located in an attic, basement, closet, or crawlspace. To access the coil, you may need to remove a panel or other covering to get to it.

  3. Remove the evaporator coil housing: Once you have located the coil, you will need to remove the housing that covers it. This housing is secured with screws or bolts. And can be removed by loosening them and carefully lifting them off. Be careful when handling the housing, as it may be heavy and cause injury if dropped. (Side note: to thoroughly clean the evaporator coil, it may need to be removed from the system. Doing so involves removing the refrigerant from the system. Disconnecting the coil from the copper line set. Cleaning. Reconfiguring the coil and recharging the system with refrigerant.)

  4. Clean the fins: The evaporator coil is made up of thin metal fins that are designed to help transfer heat. You can use a soft brush or a can of compressed air to clean the fins. Be gentle when cleaning the fins, as they are delicate and can be easily damaged.

  5. Rinse the coil: Once you have cleaned the fins, you can rinse the coil with water. You should not use a strong stream of water, as this could damage the fins. Instead, use a gentle stream of water and wash the coils from the inside out. Rinse the coil thoroughly to remove any dirt or debris stuck to the surface.

  6. Let the water drain out of the drain pan and through the AC condensate line. After rinsing the evaporator coil, you will need to let the water drain out of the drain pan. This is important to prevent water from accumulating in the pan. And causing problems with the HVAC system. Be careful not to let water leak into other system components, as this can cause damage. In up-flow systems, this is particularly important. As water can leak down to the heat exchanger, blower wheel motor, and electronics in a gas furnace. Or a blower wheel motor and electronics on an air handler.

  7. Clean the surrounding area. After you have cleaned the evaporator coil, it is important to clean the surrounding area. This may include removing any dust or debris accumulated in the air handler or furnace. As well as cleaning any other components that may have been exposed during the cleaning process.

Cleaning the condenser and evaporator coils are essential in maintaining your HVAC system. By following the steps outlined above and cleaning the coil properly. You can ensure that your system works at its best. And maintains a comfortable indoor environment.


It is important to note. Cleaning an indoor evaporator coil can be complex and time-consuming. And it is often recommended to have an HVAC professional handle the task. A professional HVAC technician has the knowledge and experience to clean the coil. And ensure it is operating correctly.


Frequently asked questions

Can I clean my AC coils myself?

Yes, cleaning your AC coils yourself is possible. But having a professional take care of the task is generally recommended. Cleaning the coils can be complex, time-consuming, and require special tools.

Is AC coil cleaning necessary?

Does cleaning AC coils make a difference?

How often do AC coils need to be cleaned?

Conclusion

In conclusion, AC coils play a crucial role in the functioning of an HVAC system. They are responsible for transferring heat. And cooling the air circulating throughout the home. There are different types of coils in an AC system. Including the evaporator and condenser coils.


To ensure the system runs efficiently, clean and maintain the AC coils regularly. Look for signs of a dirty or malfunctioning coil. Such as high static pressure, a frozen coil, or a noisy compressor motor. And if you suspect that your AC coils may be dirty, it is important to follow the proper steps to clean them. If you are not comfortable or familiar with cleaning the AC coils, it is recommended to hire a professional HVAC technician to do it.


Properly maintaining your AC coils can help extend your HVAC system's life. And ensure that it works best to keep your home comfortable.

If you are ready to take the next step. Consider scheduling a professional AC coil cleaning. By having a trained and experienced HVAC technician clean the coils. You can be sure that your AC coils are cleaned properly and that your system is running at its best.

Connect with an HVAC pro. And get started on ensuring that your system is running efficiently and effectively.

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