5 Signs Of Bad Evaporator Coil

The evaporator coil is the main component of an AC unit. Together with the condenser coil, the evaporator cools down the air, sent back indoors to cool down an area. Issues like a dirty air filter, leaks, and unusual noises are warning signs that an evaporator coil is going bad.

An air conditioning system is consists of various components that do specific things. When one component goes bad, the whole system will not work as intended. And even if it does, there is a problem in efficiency and functionality. One such essential component is the evaporator coil. 

But just like other human-made devices, an evaporator coil will eventually turn bad and fail. How does an evaporator coil work? How do you know if it’s turning bad already?

What are the common issues that occur to the AC when the evaporator malfunctions? Let’s find out more about evaporator coils in this blog. 

What Does An Evaporator Coil Do?

In its simplest term, the evaporator coil makes the cooling effect possible. Warm air will circulate through this coil and gets cool down. This cooled air is dispersed back indoors (to a house or a room,) effectively lowering the temperature. Some AC units come with heat pumps for heating purposes, which send back warmer air to the area covered.

How Does An Evaporator Coil Works?

Both the evaporator and the condenser coil are responsible for moving the air in the system. But the actual cooling happens in the evaporator coil. This coil holds the chilled refrigerant, which is responsible for converting warm air to cold air. 

The blower fan will blast warm air directly to the evaporator coil, wherein the refrigerant converts it into colder air. As a result, the refrigerant gets all the heat from the warm air. It gets flushed out of the system via the condenser coil. 

Both the evaporator coil and the condenser coil needs to be maintained regularly. If any of the coils malfunctions, your AC will not work correctly or not at all. Hence, a checkup of your AC coils daily is a recommended thing for maintenance. 

How Can You Tell If An Evaporator Coil Is Bad?

Prevention is always a better option. Regularly cleaning your AC component is better than waiting for them to get bad. However, the coil will eventually give up and will require repair or replacement. Here are some of the signs that can indicate a bad evaporator coil. 

1. Warm Air From The Vent

Evaporator coils facilitate air cooling using the refrigerant installed into them. Hence, if the vent suddenly starts to blow warm air, it’s likely that your evaporator coil has some issues. There will be no warm air from the vent if the evaporator coil is operating as intended. 

2. Frequent Malfunctioning

An AC unit can turn on and off automatically. Once it fulfilled the temperature in the thermostat, the evaporator coil will stop venting off cooled air. But if the frequent on-and-off cycle happens without the air getting cooled, there’s a big chance that a leak had occurred. 

3. Strange Noises During Operation

ACS is meant to operate as silent as possible. So if your evaporator coil started making strange noises while functioning, it’s worth the time to check. If your AC started to make noises along with other signs on the list, you might want to consider calling a professional for help.

4. Low Indoor Air Quality

Is your AC unit venting out air with an unpleasant smell? One of the main reasons for low indoor air quality is a dirty evaporator coil. Bacteria and other kinds of nasty things can start to grow on the coil, especially there is no regular maintenance. The growth of mold and gunk layers will affect the air coming out of the vent. 

5. AC Does Not Turn On At All

There’s a lot of things and malfunctions that can make the whole AC stop working. In most cases, this can mean that your evaporator coil is beyond repair and needs a replacement. 

Common Evaporator Coil Problems

The list mentioned above is the signs that indicate evaporator problems. If your AC is showing one or more signs mentioned above, your evaporator coil might be having issues listed below. All of these problems reduce the cooling ability of your AC unit.

  • Dirty Air Filter – If you’ve been postponing replacing your air filters, here’s a motivation to do so. These nasty filters can cause a lot of damage to your evaporator coil. If it’s too dirty, it restricts the airflow that the evaporator coil receives. Although the problem is in the air filter, it creates a problem with the coil’s operations. 
  • Frozen Evaporator Coil – Most AC users ignore if there’s ice that develops in their equipment. After all, this ice might be a part of cooling the air. Unfortunately, ice appearing in the evaporator coil is a big problem. It means that the coil cannot absorb the warm air properly and instead starts freezing any condensation in the area. 
  • Dirty Evaporator Coil – Dirt and grime layers might develop in the evaporator coil, especially if you don’t regularly replace your air filter. This development happens when dirty air enters the evaporator coil. This problem restricts the airflow coming through the coil, which causes a huge inefficiency. 
  • Evaporator Coil Leak – AC leaks happen due to freezing. Once the AC unit is turned off, the ice that develops during its operating time will melt away. In this case, you might need to repair the problem with your frozen evaporator coil. Refrigerant leaks, however, are a different problem that occurs when the coil lining is corroded. When refrigerant leaks happen, getting professional help is recommended. 
  • Faulty Blower Motor – The blower motor is responsible for redirecting the air into the evaporator coil for cooling. But just like other motors, this component is affected by wear and tear. If it stops working, the evaporator coil will stop operating because it doesn’t receive any air to cool. 

Some common evaporator problems are fixable, even with little HVAC fixing experience. However, if you have no HVAC experience before, you might want to consider getting some help from an HVAC professional. 

Replace Or Repair Evaporator Coil

There are certain instances when you can still repair your evaporator coil or when it’s better to replace them. You might be inclined to choose between the two, depending on your current budget. Some evaporator coil problems are repairable, but there are other problems like refrigerant leaks that need replacement. 

If your evaporator coil problem is fixable via cleaning, removing clogs, and replacing the air filter, then DIY remedies are accepted. But if the component needs replacement, the best course of action is to call for the nearest HVAC service provider. If you prefer to clean your evaporator coil, you can d so without removing it.

Other Factors

Various types of evaporator coil are available for installment. Depending on the type of coil, the prices can quickly increase. If your evaporator coil is cased, expect a hike on your repair or replacement bills. These products are 25% to 75% more expensive than their uncased counterpart. 

Don’t forget to include the evaporator coil brand as a factor, especially if the plant is propriety. According to data from Home Advisor, Goodman or Amana brand and Aspen are the cheapest to repair or replace. If you have a Lennox AC, expect a higher bill. 

How Much Does It Cost To Repair Evaporator Coil?

If the problem in your evaporator coil is reversible by simple actions, then it’s better to repair it. For example, freezing and dirty coil can be easily dealt with by cleaning, replacing the air filter, and looking at the refrigerant line. It would be easier, cheaper, and more convenient. 

The average cost of replacing an evaporator coil is $1.000. However, this price tag can increase up to $2,000, especially if it is not covered by insurance anymore (for defect replacements). Most AC problems don’t need replacement to fix something. Keep in mind that repairs can turn into replacements if other issues are found. 

How Much Does It Cost To Replace Evaporator Coil?

Eventually, you will need to replace your evaporator coil after long usage. For this purchase, the recommended amount to save up is $1,000. Allocate more funds if your evaporator coil is cased or if it’s more than two tons in weight. More expensive brands will also have an above-average replacement price. Don’t also forget to add the labor cost to your budget. 

There are cases wherein repair is more expensive than repair. One such issue is when there is a refrigerant leak. AC coil leak repair costs can reach up to $1,600, which is as good as replacing the whole thing. You might as well get a new one, as you can also get recharging for the refrigerant. 


The evaporator coil is a crucial AC component that needs maintenance regularly. Once it starts to go bad (warm air from the vent, strange noises, odor, etc.), it might need either repair or replacement. Depending on the cause of the problem, you might have to opt for repair or replace the component.