Evaporator Coil Leaks: Signs, Symptoms & How To Fix

Inside your AC is the evaporator coil that absorbs heat from your house, and using the refrigerant gas, it transfers it outside. Pretty simple right?

But what happens if things go wrong and the evaporator coil leaks? Well, it can lead to a variety of issues such as your AC unit freezing, turning off, or critical components failing.

Want to know more about leaky evaporator coils and how to fix them? Read on!

What Causes The AC Evaporator Coil To Leak?

Chemical Reaction

One of the most common causes of AC evaporator coil leaks is a chemical reaction! It happens when high humidity, “volatile organic compounds (VOCs),” and copper come together. Once combined, they make a formic acid solution that erodes the copper altogether, leading to coil leakages.

Humid Climate

Do you know AC evaporator coils leak most in humid environments? That’s because when VOCs merge with moisture, they attack copper evaporator coils, forming leaks.

Volatile organic compounds are gases most everyday household appliances and products emit. For example, they may come from cleaning products, flooring materials, air fresheners, dry cleaning, paint, some cosmetics, among several other things.

Mold Or Biofilms Growth In The Evaporator Coil

Some other reasons for coil leakages include biofilms and mold growth on the AC evaporator coil. Both are capable of eroding copper slowly, leading to an eventual leak if overlooked.

Signs Of A Leaking AC Evaporator Coil

It Takes A Long Time To Cool

If you have evaporator coil leakages, the refrigerant will start to leak out slowly. Without an adequate cooling agent, your AC unit will work significantly harder and take a longer time to cool. If you believe your system takes much time than usual, chances are the coil is leaking.

Airflow Feel Weak Or Doesn’t Turn On Right Away

When you turn on your air conditioning unit, it should promptly toss away cool air through air vents. However, if you believe the air stream is weak or doesn’t turn on right away, it may indicate that you’ve got an evaporator coil leak.

Warm Air Coming Out From The Vent

If you notice warm air coming out from the vents, here’s what you need to do:

  1. First, make sure the thermostat isn’t on ‘heat’ function
  2. Then, ensure it’s on the ‘auto’ function and not on ‘fan.’ That’s because a fan setting provides air to pass through the vents even though the AC isn’t going through the cooling cycle
  3. After that, check if the air filters are clean or not. Blocked or clogged air filters prevent air conditioners from providing their maximum performance.

If everything works fine, but you still observe lukewarm air blowing from vents, chances are you have a coil leakage.

Hissing Or Bubbling Sounds

A hissing or bubbling sound from coils behind an external condenser or inside an air handler indicates evaporator coil leaks that you should promptly address because it involves harmful chemicals.

If that’s the case, avoid touching the evaporator coil lines in the cooling system and immediately call your HVAC technician.

High-Humidity Levels

When your air conditioner cools down your home, it simultaneously dehumidifies it. Similarly, if it’s unable to take out heat from the house due to insufficient refrigerant, it will fail to remove moisture as well.

If you note indoor humidity levels are higher than usual, call your HVAC technician as you may have an evaporator coil leak.

Increased Electricity Bills

When the AC unit doesn’t function properly, it works harder and longer than usual, resulting in higher monthly electricity bills.

Carefully review this years’ bills and match them with last year’s; you’ll get to know whether the system is working inconsistently or not.

Increased Electricity Bill

How To Fix Leaking Evaporator Coil Of Your Air Conditioner

How to fix a leak in an evaporator coil? Well, it is recommended to call a professional to fix it right away. However, while repair jobs are best when left to experts, fixing a coil leak yourself can save you several maintenance costs.

Nevertheless, a technician will help inspect and confirm the issue. Once the problem is confirmed, the professional may replace the evaporator coil right away. Some technicians may add an evaporator coil leak sealant, while some may replace the coil entirely. A new evaporator coil may cost you big, but it helps cool your home quickly and efficiently.

Here’s how you can fix an air conditioner’s leaking evaporator coil yourself. If your evaporator is still under warranty, getting it replaced by a professional would be best. However, if it has crossed way past the warranty, a quick fix may be helpful but won’t fix the problem entirely.

You can add an evaporator coil leak sealant to minimize costs. Sealants work for small to moderate leaks with a 50% success rate. You can add a sealant to your a/C evaporators, copper lines, and condensers. They travel through the coil tubes looking for potential leaks and fill them in.

While this method is cost-effective, you may need multiple applications depending on the damage, further adding to costs in the longer run. Furthermore, there may be chances your cooling system has run out of gas. In such cases, adding a refrigerant may be the best possible solution. It’s cost-effective and will minimize your investment if you plan to sell your house anytime soon.

However, much like sealants, this is a temporary solution and can be costly in the longer run. Furthermore, adding refrigerants from time to time can cause internal damage to your AC system. Therefore, if you want a short-term solution, this method may work best for you.

If nothing works for you, replace the evaporation coil entirely. Installing a new evaporator coil will not be that expensive compared to adding refrigerant gas and sealants from time to time. Paying more for a new evaporator coil will replace the costs of repairing and maintaining damaged coils later on. In addition, a new coil will improve the efficiency of your AC and minimize energy costs.

How To Prevent Evaporator Coil Leaks?

The first thing you must do to prevent evaporator coil leakages is to stop using the products that caused them in the first place. Stop using cleaning products that contain high levels of volatile organic compounds. When purchasing these detergents, make sure they do not contain harmful chemicals that your AC units could absorb along with the air.

Preventing coil leaks may sound like a lot of work, but it will keep your AC and heating units free from internal damage, saving repair and maintenance costs in the future. Open windows and doors 10 minutes before turning the AC systems on to allow fresh air inside the room. Inspect the coils to look for potential damage and fix the problem right away.

Cleaning the coils yourself can be very beneficial. However, if you are not experienced with AC systems, a slight mistake can pinch a hole in the fragile evaporator tubes. Therefore, hire a professional expert to conduct an in-depth inspection of your heating and cooling systems and get them cleaned once a month to prevent dirt and mold accumulation.

Prevent Evaporator Coil Leaks

Why Do Evaporator Coils Leak On Popular AC Products?

Trane AC Units

Trane air conditioning systems constantly rank higher in customer dependability and satisfaction mainly because they manufacture some of the best HVAC units with superior components and features. Nevertheless, like other famous HVAC technologies, Trane AC units also experience issues.

If your Trane air conditioner faces an evaporator coil leakage, chances are it’s due to a chemical reaction, precisely formic acid.

Here’s how you can fix it:

  1. Add coolant or refrigerant
  2. Add  ultraviolet ((UV) lights to your air handler
  3. Use “Energy Recovery Ventilator (ERV)”
  4. Lastly, minimize the VOCs

Related Article Trane Air Conditioner Reviews

Amana AC Units

Amana air conditioning systems are affordable, robust, and reliable. As a result, it’s gaining immense popularity, and rightly so as it boasts some fantastic features that improve the unit’s overall efficiency and performance. Unfortunately, though they make some of the most affordable models, their installation can be costly.

Despite being a good brand, their products can also face problems, like other appliances. For example, if your Amana AC unit is experiencing a leak in the evaporator coil, it may be due to biofilms, mold growth, or formic acid.

Here’s how to fix your Amana air conditioner’s leaky coil:

  1. Use a sealant to seal coil leaks
  2. Add more refrigerant
  3. If it’s an expensive repair, consider replacing it

Related Article Amana Air Conditioner Reviews

Bryant AC Units

Bryant is a famous HVAC company manufacturing high-quality and reliable air conditioners and other HVAC appliances. They offer some of the best warranty claims in the market. However, they are relatively expensive units.

If you’ve got a Bryant AC unit and its evaporator coil is leaking, you can smoothly fix it. Typically, leaks result from mold growth, humidity, corrosion, or chemical reactions such as formic acid.

Nevertheless, here’s how an easy way to fix the problem:

  1. Change furnace filters routinely to avoid corrosion
  2. Add more coolant
  3. Use a sealant
  4. Replace the coil with a new one

People Also Ask (FAQ)

How much does it cost for a HVAC contractor to fix a leaking evaporator coil?

It varies depending on various factors such as model, location, etc. Nevertheless, an HVAC professional may charge you anywhere from $300 to $1500 to fix a leaking evaporator coil.

How long do ac evaporator coils generally last?

To ensure your evaporator coil lasts longer, keep your air conditioning system maintained. If you perform routine care and maintenance, the coils can easily last ten to fifteen years or more.

Is it worth replacing the evaporator coil rather than fixing?

If your AC model is relatively newer and experiences a leaky evaporator coil, it’s better to replace the coil rather than fixing. That’s because sometimes coil leaks can be expensive to repair.

How often should the evaporator coils be cleaned?

One must clean evaporate coils every year. If you keep them clean, you’ll minimize electricity consumption and overall utility costs. However, if they remain dirty, they will increase electricity usage by 30%.

How much does it cost to replace the evaporator coil?

Though it varies from location to location and model to model, the average cost to replace a leaking evaporator coil is $1000, with a usual range of $500 to $2200.


Evaporator coil leaks are common AC problems. They are pretty troublesome for homeowners as they minimize energy efficiency and performance and drastically increase your monthly utility bills. Moreover, they can also damage other components, leading to more costly repairs. Therefore, promptly addressing leaky coils is the only viable solution.

Josh Mitchell

Josh Mitchell

My name is Josh and I am obsessed with DIY and improving my family home. HVAC topics can be tricky for homeowners so I decided to share my knowledge on the subject. When I am not working on DIY projects, you can find me at the beach or my local coffee shop.