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What Is the Evaporator Coil in HVAC Systems (and Why Is It So Important?)

Jenna Jonaitis
Written by Jenna Jonaitis
Updated November 18, 2021
A young couple talking while woman using the thermostat
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Without a well-functioning evaporator coil, your AC and heat pump won’t work properly

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No matter if it’s hot or cold outside, an evaporator coil plays a key role in keeping your home comfortable. Not only does it hold refrigerant, but it absorbs heat from the air.

Learn all about your evaporator coil, including why it’s so important and how to know if it’s damaged or dirty. We’ll also help you decide if you should replace your evaporator coil based on the age and condition of your AC system.

What Is the Evaporator Coil in HVAC Systems and How Does it Work?

The evaporator coil holds the refrigerant and absorbs heat no matter if it’s your air conditioner or heat pump. The indoor evaporator coil usually sits inside the air handler or blower compartment of your AC unit or is attached to your furnace. The evaporator coil connects with the condenser coil, and both work together to complete the heat exchange process.

Air Conditioner

The evaporator coil holds the refrigerant and absorbs heat and humidity from your home’s air. The blower pushes the cooled air into your ducts to supply each room with conditioned air. As the refrigerant gets warm, it condenses and travels to the condenser coil outside. The compressor then compresses the refrigerant back to liquid form to start the loop again.

Heat Pump

The evaporator coil and its refrigerant absorb heat, so the blower can push hot air into your ducts and supply your rooms with heated air. When temperatures fall below a certain level, auxiliary heating elements may kick in to supply heat.

Importance of Cleaning and Maintaining Your Evaporator Coil

Routine maintenance and cleaning keep your evaporator and condenser coils running efficiently and your AC and heat pump too. Dirty coils can increase your energy usage—and your monthly bill.

You might also experience other problems like poor performance, a frozen evaporator coil, and breaking. Hiring a pro for an annual cleaning and tune-up will help maintain optimal function and prevent larger issues.

How Long Do Evaporator Coils Last?

Evaporator coils last 10 to 15 years if you perform regular maintenance. This timeframe is equal to the average lifespan of an AC unit. So if your evaporator coil goes out near the end of the AC’s life, you may consider replacing your whole AC system instead of replacing the evaporator coil.

6 Signs of a Damaged or Dirty Evaporator Coil

A damaged or dirty evaporator coil leads to poor performance, and if it’s not fixed, further problems can arise.

Here’s how to tell if your evaporator coil is dirty or damaged:

1. Warm air is coming from your vents

2. Your AC unit doesn’t turn on 

3. Your AC starts and stops but isn’t cooling your home like usual

4. Refrigerant is leaking near your indoor cooling system

5. You hear unusual noises coming from your AC system, such as hissing and rattling 

6. Your air conditioner is constantly running, working overtime to cool your house

Reach out to a local HVAC technician sooner than later to look into the issue or clean your air conditioner coils.

Common Evaporator Coil Issues

If your evaporator coils aren’t working efficiently, it could be due to a few reasons. Here are the most common evaporator coil problems:

  • Dusty or dirty evaporator coil

  • Dirty air filter

  • Refrigerant leak, leading to low refrigerant levels

  • Frozen evaporator coil

  • Low refrigerant levels

  • Mismatched evaporator and condenser coils

As a homeowner, you may be able to handle simple cleans such as brushing away dust from the indoor evaporator coil or replacing a dirty air filter.

But more extensive issues such as a refrigerant leak or frozen evaporator coil are best left to an HVAC professional. Getting a leak fixed properly will save you time, money, and headache.

Should You Replace Your Evaporator Coil?

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If your evaporator coil has a leak, it’s usually better to replace the coil than repair it. It can be expensive to repair the coil and refill the system with refrigerant. Over time, a leak erodes the inner lining of the evaporator coil and weakens the metal. The outer liner can also sometimes corrode, causing more refrigerant leaks.

Get a few quotes from local HVAC professionals to help you decide. It might make more financial sense to get a new AC unit than replace the evaporator coil.

Cost to Replace Your Evaporator Coil

It costs between $600 and $2,000, with the average being $1,300, and it costs about the same to repair it. That’s why it’s almost always better to replace an evaporator coil than repair it.

Talk with your contractor to determine if it’s worth replacing your evaporator coil or your whole AC system, usually based on the age and condition of your unit.

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