Understanding the Function of the Evaporator Coil in Air Conditioning Systems

You don’t want your AC breaking down in the hot UAE summers. The AC evaporator coil is one major component that ensures your unit runs smoothly. Understanding the role of an evaporator coil unit and how to maintain it can help you prevent the discomfort of a faulty air conditioner right when you need it the most. In this article, we will explore evaporator coils, uncovering what they are, how they work, common issues, maintenance tips, and more.

What is an Evaporator Coil?

An evaporator coil unit is a vital part of air conditioning systems that cools indoor air. It works with the condenser coil to complete the heat exchange process and cool your home or commercial space. The evaporator coil is a type of heat exchanger device.

The AC evaporator contains a refrigerant that absorbs heat from the indoor air, transforming it from hot to cool and comfortable. The coil is typically made from materials that conduct heat easily, such as aluminum, copper, or steel.

How does an Evaporator Coil Unit work?

The AC evaporator coil location is in the indoor unit of your air conditioner. It is positioned near the air handler or furnace, depending on your system type. The coil is connected to the rest of the system via pipes. A refrigerant, a chemical substance with low boiling and freezing points, circulates through these pipes.

The refrigerant enters the exothermic evaporator coil as a low-pressure liquid. As warm indoor air passes over the coil, the liquid refrigerant evaporates, absorbing heat from the air. As the refrigerant evaporates, it cools the air passing over the coils, which is then redistributed throughout your space. This transformation from a liquid to a gas state is exothermic

Now in a vapor state, the refrigerant enters the outdoor condenser unit to release the absorbed heat into the atmosphere. The refrigerant condenses into liquid form and returns to the evaporator to repeat the cycle.

Where Are Evaporator Coils Used?

Evaporator coils are used in various applications, including:

  1. Residential air conditioners: Most homes in the UAE rely on air conditioning units with evaporator coils to combat the heat.
  2. Commercial HVAC systems: Office spaces, hotels, and malls use large-scale air conditioning systems with multiple evaporator coils.
  3. Refrigerators: The evaporator in your fridge keeps your food cool and fresh.

What is the Difference Between an Evaporator Coil and a Condenser Coil?

While both the evaporator and condenser coils are essential components of an air conditioning system, they have distinct functions. As we mentioned earlier, the evaporator coil cools indoor air, while the condenser coil releases the heat absorbed by the refrigerant outside, allowing the cycle to continue.

The evaporator unit is typically located in the indoor unit of an air conditioner or refrigeration system, while the condenser coil is located in the outdoor unit.

Common Evaporator Coil Problems

Like any machinery, evaporator coils can encounter issues over time. Some common problems include:

Frozen Coil

If the evaporator gets too cold due to limited airflow or refrigerant issues, condensation can freeze, leading to ice buildup. This ice further reduces airflow and decreases cooling efficiency. An HVAC professional can inspect your frozen evaporator coil and defrost it, following the necessary measures.

Dirt and Dust Buildup

Over time, dust and debris can accumulate on the coil’s fins and coils. This buildup restricts airflow and reduces the coil’s ability to absorb and release heat efficiently. If your AC is malfunctioning, consider calling a technician to inspect your coil.

Refrigerant Leaks

Refrigerant is essential for the cooling process in your HVAC system. A leak in the evaporator unit can cause a drop in refrigerant levels, leading to decreased cooling performance. If you notice an oily substance around your coil, consider scheduling for maintenance with your technician.


Evaporator units are typically made of copper or aluminum, which can rust over time. Corrosion weakens the coil’s structure and can lead to refrigerant leaks and compromised performance.

Improper Sizing

An incorrectly sized evaporator unit can cause your HVAC system to run inefficiently, leading to increased wear and tear. If you have a too large or small evaporator coil, consider replacing it with an ideal one. A professional can help you select a coil that matches your needs using an evaporator coil sizing chart.

Signs That Your Evaporator Coil Unit is Faulty

A faulty evaporator unit can significantly impact the performance of your system. Recognizing the signs of a faulty coil is essential for timely maintenance and repairs. Here are some signs you should look out for.

  1. Warm air blowing from vents: When your evaporator unit is not functioning correctly, your AC system may blow warm air instead of cool air.

  2. Reduced cooling capacity: If you notice that your HVAC system is no longer effectively cooling your space, it could be a sign of an evaporator problem.

  3. Strange noises: Unusual sounds like hissing or gurgling can indicate a problem.

  4. Water leaks: Excess condensation or water around the unit could point to issues.

  5. High energy bills: A faulty coil can make your AC work harder, leading to increased energy consumption.

  6. Uneven temperature distribution: Inconsistent temperatures throughout your home or building can indicate an issue with the coil. Some rooms can be too hot while others remain cool.

  7. Water leakage: Excessive water pooling around the indoor unit or moisture stains on walls can indicate a clogged or malfunctioning coil.

How to Maintain Your Evaporator Coil Unit

Proper maintenance is key to ensuring the longevity of your AC system. Here is how you can keep your evaporator coil unit in great condition.

Change or Clean Air Filters

Dirty or clogged air filters restrict airflow, causing the coil to work harder and collect more dirt. Check your filters regularly and replace them every 1-3 months or as the manufacturer recommends.

Keep the Surrounding Area Clean

Ensure that the area around the indoor unit is clean and free from dust, debris, and obstructions. A clutter-free space allows for better airflow.

Inspect for Refrigerant Leaks

Look for any signs of oil or refrigerant leaks around the coil or refrigerant lines. If you suspect a leak, contact a technician to diagnose and repair it.

Schedule Professional Maintenance

While you can perform some maintenance tasks yourself, it is crucial to schedule professional HVAC maintenance. A qualified technician can perform a comprehensive inspection, clean and service the entire system, check refrigerant levels, and make necessary adjustments or repairs.

Replace your Evaporator Coil Unit

If your evaporator is beyond repair, you will need to replace it. AC evaporator coil replacement ensures you continue living comfortably even in extreme weather conditions in the UAE. Replacing the unit yourself could be risky. It would be best to leave the job to an expert.

How to Check Evaporator Coil

While some maintenance tasks are best left to professionals, you can check your coil for visible issues. Make sure to turn off the power before attempting any inspection.

  1. Inspect for ice: If you see ice buildup, it is a sign of trouble.
  2. Look for leaks: Check for any signs of refrigerant leaks, such as oily spots.
  3. Corrosion or damage: Inspect the coil for any signs of corrosion or physical damage. Corroded coils may develop leaks over time and compromise performance.
  4. Call a professional: If you suspect an issue with your unit, contact a technician for a thorough inspection.

FAQS About Evaporator Coil Units

Is the evaporator coil used for heating?

Yes, an evaporator is commonly used in heating, cooling, and air conditioning systems. In a cooling system, the coil absorbs heat from the indoor air to cool the space. In a heating system, it can be used in a heat pump to extract heat from the outside air and transfer it into the indoor space to provide heating.

Is evaporator same as radiator?

No, an evaporator and a radiator are not the same. These components serve different purposes in different systems. The evaporator is a component found in air conditioning and refrigeration systems. It absorbs heat from the surrounding air.

On the other hand, a radiator is part of an engine’s cooling system in vehicles and generators. Radiators dissipate heat generated by the engine to prevent it from overheating.

How long do evaporator coils last?

The lifespan of evaporator coils can vary depending on factors such as the quality of the coil, maintenance, usage, and environmental conditions. On average, a well-maintained evaporator can last anywhere from 10 to 15 years. However, some coils may last longer, while others might need replacement sooner, depending on the level of care.

Where is the evaporator in the refrigerator?

In a refrigerator, the evaporator is typically located inside the freezer compartment. It consists of a coil or series of coils that help to cool the air inside the refrigerator. When the refrigerant inside the evaporator coils evaporates, it absorbs heat from the food and the air inside the fridge, keeping the contents cold.

Final Thoughts on Evaporator Coils

An evaporator coil is necessary for the UAE’s scorching heat. However, this component is also prone to mechanical issues and damage. Understanding how it works, how to maintain it, and when to replace it can help you ensure the longevity and efficiency of your AC unit. Remember to keep checking your coil for signs of damage like corrosion, leaks, strange noises, and more. For more insights regarding evaporator units, reach out to us today.