What Does an Evaporator Coil Do?

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Updated February 8, 2023

As summer temperatures roll in, many turn on their air conditioner only to find that their power is weak or blowing lukewarm air. Even the best air conditioners need to be maintained, and that’s why in this article, we’ll analyze the question, “What does an evaporator coil do?” There would be no ability to cool air temperature without the evaporator coil (or condenser coil). For a central air conditioner, the evaporator coil is part of the outdoor unit. In window and portable units, they are inside the unit’s body. The coils are filled with liquid refrigerant, which the system keeps cold. As hot air is funneled in from the vents and passes over the coils, the heat is absorbed, so the air becomes cool.


  • The evaporator coil is responsible for removing the heat from the air being cycled through an air conditioner.
  • Keeping the evaporator coils clean and free of debris can significantly increase energy efficiency and help avoid expensive repairs.
  • An evaporator coil consists of a copper tube that regulates refrigerant flow. The coil becomes frosted if dirty, which impedes the unit’s cooling power.

For more information on air conditioners, we have a great resource explaining what energy saver mode on an air conditioner does. Our other info articles talk about understanding E1 on an air conditioner and what is P1 on an A/C.

Those who are interested in air conditioner operation, read our guides on how to set the air conditioner thermostat and what does the fan do on an A/C.

Insider Tip

Depending on how much you use your AC unit, you should get regular service or check at least once a year.

As you can see, the cooling process would be impossible without the evaporator coils. This means that your air conditioning unit needs to keep free from refrigerant leaks, and you must conduct frequent repairs and checkups to keep it in the best operation.

Also, if you’re seeing error codes pop up on your system, check out what F6 means on an air conditioner.


A dirty or eroded evaporator coil can cause severe damage. Perform routine checkups and ensure no erosion or debris builds up around the coils to avoid this.

Caring for Your Evaporator Coils

When the coils become dirty, the heat exchange process becomes obstructed, leading to frozen evaporator coils. In addition, when an AC coil can’t properly do its job, water vapor collects outside the cold coils, causing them to frost over.

To avoid this, make sure that your unit’s refrigerant levels are correct, that the air filter is replaced, cleaned, or washed routinely, and that there’s no buildup of residue or debris around the coils or outside the unit.

STAT: Dirty coils can increase your energy use by up to 30%. (source)


Why is having clean evaporator coils necessary?

Taking the necessary steps to have clean evaporator coils keeps energy bills down, cooling efficiency at its peak, and reduces maintenance costs and inconveniences.

What can I do to prevent dirty evaporator coils?

The best way to prevent dirty evaporator coils is to ensure air filters are clean and replaced or washed as part of regular maintenance. A dirty air filter leads to low-quality air being cycled through the condenser and evaporator, leading to a higher chance for the evaporator coil to get dirty.

When does an evaporator coil need to be replaced?

Usually, when an evaporator becomes eroded, it’ll need to be replaced. The average lifespan of an evaporator coil is 10 to 15 years, but a professional HVAC serviceperson can check to see how much life is left in your unit.

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