How to Identify a Leaking Evaporator Coil: The Causes

Every air conditioner has an evaporator coil in its blower compartment. This part of the cooling system plays a vital role in the operations of your AC. This part is also prone to leaking, which can be difficult to identify for ordinary homeowners. This article will tell you why leaks in the evaporator coil occur, how you can identify them, and how you should deal with them. 

What Is an Evaporator Coil?

The AC’s evaporator coil is also known as the evaporator core. The evaporator coil is responsible for holding the cooled refrigerant inside the AC. It absorbs the heat from the house and converts it into cold air. If you open your AC system, you will find it near the blower fan. It can sometimes be attached to the furnace. 

Why Does the Evaporator Coil Leak?

A leak can occur in your evaporator coil if small holes start to develop. The most common reason behind it is the presence of volatile organic compounds (VOCs). Here is how it usually takes place:

  • Some household products such as aerosol air fresheners, adhesives, and cleaning products contain these VOCs. 
  • When these VOCs get mixed with the moisture in the air, they can become acids.
  • The acid can cause pinholes in the coil, resulting in leaks.

However, these holes are so tiny that only an HVAC technician can diagnose them. 

How to Know You Have a Leaking Evaporator Coil

Although the holes are hard to determine yourself, there are telltale signs that can help you recognize that something is wrong with your evaporator coil. You know you have leaking coils if you notice any of the following:

  • The air conditioner takes longer than usual to fully make a room cooler. The AC usually works harder if there are not enough refrigerants converting warm air into cool air. A lack of refrigerants could stem from leaks in the evaporator coil. 
  • The air does not flow right away when the unit is turned on. It might take some time, and the air released often feels lighter than it should be.
  • You feel warm air coming out through your vents even though the AC is turned on.
  • You hear hissing noises outside your AC unit. 
  • There is an unpleasant smell coming out of your heating and cooling system. 

What You Should Do

Remember that your AC unit would not run out of refrigerants unless there is a leak in your coils. Once you notice these symptoms, turn your AC unit off and call an HVAC technician so you can have the system checked immediately. Make sure to turn it off, as keeping it running can only damage the machine further.

After calling an HVAC technician, expect them to recommend you replace your evaporator coil. A new evaporator coil could cost you more, but it could make your cooling system perform better again. 

To make sure the problem does not result in a leaking coil again, make sure to do the following: 

  • Schedule regular HVAC system maintenance and have a technician examine your system at least twice a year. Make sure they pay attention to the evaporator coil. 
  • Regularly change your filter to make sure the air moves efficiently.
  • Make sure also to ask the technician to conduct regular cleaning of all the system’s parts.


Although the evaporator coil is not that visible, it is important to clean and maintain it to keep your AC system efficient. If it is not appropriately maintained, it can cause more expensive problems in your system. Take note of the symptoms above and contact professional HVAC technicians as soon as you notice any issues.

If you live in Indiana and need air conditioning or furnace repair or replacement near you, Good Guys Home Service can help. We are a company created and operated by technicians, so we know what we do. Our technicians have at least five years of experience in the field and are highly skilled in the trade. Download our app now!


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