How The Coils In An Air Conditioner Work


Most people know that their air conditioner has coils that will help it cool the air.  Many of these people will not know how these coils work or the fact that there are evaporator and condenser coils in the unit.  If you want to better understand how your air conditioner works, you need to know more about the coils and the processes they go through.  This information from can also help you troubleshoot any potential problems with your air conditioning unit.

What Is An Evaporator Coil?

The part of your air conditioner that absorbs heat is the evaporator coil which is also known as the evaporator core.  This coil will generally be located close to the air handler which is the location of the blower fan.  Evaporator coils are generally made from copper, aluminum or steel as they offer the best heat conductivity.

The average residential air conditioner will have a U-shaped evaporator coil.  The coil will also be set into panels which are generally positioned to form an A shape.  The panels will have thin pieces of metals which are known as fins lining them.  The fins are used to bring the passing air closer to the coils to maximize the cooling effect.

When your air conditioner is running, the compressor will pull low-pressure, cold liquid refrigerant through the tubing of the evaporator coil.  Before the refrigerant enters the evaporator coil, it will move through the expansion valve which relieves the pressure in the liquid.  This is what causes it to rapidly cool and absorb the heat from the air which moves past the evaporator coil.

As the refrigerant flows through the evaporator coil, the blower fan will draw the hot air from your home and move it over the coil.  The refrigerant absorbs the heat and when this happens it will start to warm up.  As the liquid warms up it will start to evaporate giving the coil its name.

The water vapor in the air will also come into contact with the cold evaporator coil and will condense into liquid form.  This water will drip into the condensate pan which will drain out of the unit and your home.  This is the way that the evaporator coil removes the humidity from your home.

What Is A Condenser Coil?

The condenser coil will work with the evaporator coil to keep your home cool.  In order to complete the cooling process that the air conditioner runs through, you need to have a fully functioning condenser coil.  If you only have a functioning evaporator coil, your unit will not work correctly.

The condenser of your air conditioner is the large unit which is generally located outside of your home.  The whole unit is known as the condenser unit and will contain a number of components.  These components will include the condenser tubes, fins, a fan and copper tubing, valves, switches and the compressor as well as the condenser coil.

Once the refrigerant has absorbed the heat of your home, it will travel to the condenser unit.  In the unit, the low-pressure and warm liquid will enter into the compressor which applies pressure to it.  This will turn the refrigerant into a hot and high-pressure gas.

This gas will leave the compressor and enter the condenser coils.  The coils are where the refrigerant will release the majority of the heat which was absorbed from the house.  The fan which is located above the coils will blow air over them so the refrigerant loses the heat.  The condenser will generally have a number of coils which increases the amount of time the refrigerant spends in the path of the blowing air.  This ensures that all of the heat carried from your home is released.

As the refrigerant cooling in the coils, it will turn from a hot gas to a hot liquid.  Once it is back in liquid form, it will flow back through a copper tube into your home to start the process again.  This is the reason why you need to ensure that both your evaporator and condenser coils are working correctly.

Caring For Your Evaporator Coils

As the coils in your air conditioner are vital to the cooling process, they need to be cared for correctly.  A dirty evaporator coil can cause a number of problems including higher energy consumption, an ice or frost buildup, higher pressure and temperatures and impaired heat absorption.  It is important to note that even a fine layer of dust on the coils can reduce their efficiency.

It is possible for your evaporator coil to develop time pinhole leaks which is caused by corrosion.  This happens when the moisture from the condensation mixes with the chemicals that are commonly found in household air.  You can determine if you have this problem by looking for oily residue around the coils or in the drain pan.  When this happens, the coil will need to be replaced.

Caring For Your Condenser Coils

Good airflow is vital to the health of your condenser coil.  The most common threat that your condenser coil will face is a buildup of debris in the fins which reduces the air movement.  This debris will generally include grass clippings, leaves, pet hair and twigs.  When the fins are blocked, the coils will have a harder time releasing heat which lowers the overall efficiency of your air conditioner.

To remedy this problem, you should check your condenser unit periodically.  If you see any debris buildup, you need to shut the system off and using a stiff brush gently remove the debris from the fins.  It is vital that you cut the power to the whole unit when doing this to ensure that you are safe.

The condenser can also develop frost or be completely encased in ice.  If the condenser itself is clean, this is a sign that there are airflow problems in another part of your system.  This can be caused by dirty air filters as well as blockages in the ducts.  Ice can also be caused by low refrigerant levels and you will need to call a technician for this.