Here’s what you need to know.

For the average homeowner, their home’s air conditioner is a bit of a mystery. Unless you’ve had experience working with HVAC systems, you may not know the exact details of how they work. In this article, we’ll walk you through one of the most critical components of your air conditioner: the evaporator coil. This is your guide to what this part is, what can potentially go wrong with it, and why you should entrust our team with your evaporator coil replacement and repair needs.

How does the evaporator coil work?

Your air conditioner uses a process called the refrigeration cycle to cool down your home. As the name itself suggests, this is the same process your refrigerator uses to keep food cool—just on a much larger scale!

Your home’s HVAC system has several physical components. This includes an outdoor condenser unit—which is typically placed either on the ground outside your home or mounted to the roof—and an indoor blower unit. These two components are connected by the refrigerant line, which carries liquid or gaseous (more on that in a minute) refrigerant between the two in a repetitive cycle.

The air conditioner evaporator coil is located in the indoor component. This coil has one function: to absorb heat energy. As the chilled refrigerant moves through it, the air intake for your HVAC system blows warm air over it. The refrigerant absorbs this heat energy as it moves through the coil. It is then cycled to the condenser outside, where it is released into the outside air.

As this cycle repeats, over and over again, more and more heat energy is removed from your home. The refrigerant returning from outside is super-chilled. The blower fan pushes air over it, sending colder air into the living spaces of your home. In tandem, this results in cooling.

The real secret of the refrigeration process changes in pressure, which induces the refrigerant to change states (liquid or gas) and either absorb or release heat energy. It’s an incredible innovation that has made cooling homes possible for more than a century!

What about heat pumps?

Heat pumps are becoming a popular heating option for many homeowners. Despite providing winter comfort, these systems have more in common with air conditioners than they do furnaces. In effect, they reverse the refrigeration cycle described above. Instead of collecting heat energy from inside and dumping it outside, they pull heat from the outside air and carry it inside.

To “flip” the direction that which refrigerant is sent, heat pumps have what’s called a reversing valve. This allows them to operate as air conditioners in the summer months, and then switch over to heating as the nights cool down. This seasonal versatility makes them a popular option for homeowners, especially in places with relatively mild winters, like here in Central California. Heat pumps are at their most efficient when asked to deal with above-freezing nighttime temperatures—the colder it is outside, the harder it is to pull any residual heat energy from the air.

Troubleshooting evaporator coil problems

Your air conditioner’s evaporator coil is a stable, proven piece of technology. However, evaporator coils can and do run into problems. Here are three potential coil issues and what you should do about each of them.

Inadequate airflow

To function properly, your evaporator coil needs to have sufficient airflow from inside your home. Under ideal conditions, indoor air is pulled up through the air intake and the air filter to where the air conditioning evaporator coil is housed.

If something is blocking or obstructing this airflow, things can begin to go wrong. As mentioned earlier, the evaporator coil is pulling heat energy out of your home via the super-chilled refrigerant. If this heat energy is less accessible or completely inaccessible, the refrigerant could begin a runaway cooling cycle. More often than not, this results in frozen evaporator coils. As the refrigerant gets colder and colder, it eventually ices up and stops moving altogether. You’ll need to bring in one of our HVAC experts to diagnose and fix the problem.

To keep this from happening in the first place, be sure to regularly clean or replace your home’s air filter. It’s an easy thing to forget about, but an air filter that’s clogged with dust, dirt, or pet hair is not getting sufficient air through to the coils. On top of that, it’s probably making your indoor air quality much worse.

Dirty evaporator coil

Your home’s air filter does a decent job at blocking dust, dirt, and more from reaching the evaporator coils. But, it’s not a perfect solution. With enough time, the coils can become dirty and dusty. This makes them less effective at absorbing heated air. As we’ve already described, this can lead to frozen coils and other problems for your system.

An experienced HVAC technician can help you determine if your coils need to be cleaned. When you have us out for a seasonal AC tune-up and system rejuvenation, we’ll take a look at the coils and advise you on whether or not it’s time for a cleaning. Even if your coils aren’t quite dirty enough to cause mechanical issues, having us clean them can help improve your air conditioner’s energy efficiency.

Blower motor problems

As we’ve already established, poor airflow can be a problem. The blower, adjacent to the coils, is responsible for pushing hot air over the coils, ensuring that they can do their job effectively. Many frozen coils start with an issue within the blower. This blower unit has a motor that can fail prematurely.

If you’re hearing strange noises when your air conditioner first turns on, it could be the blower motor failing to start up. However, strange HVAC noises aren’t limited to just the blower: you’ll need to call our team to take a closer look.

Should I repair or replace my evaporator coil

There’s no one right answer to this question. In many cases, your evaporator coil may just need to be cleaned, or have its airflow restored by fixing the blower unit or replacing the air filter. However, in other situations, it may need to be replaced. Many coils that freeze over develop small fractures or cracks. This not only results in a refrigerant leak but generally renders the coils inoperable. Remember, the refrigeration process relies on pressurizing refrigerant to operate.

If you think you may need evaporator coil repair, you’ll need a trusted professional to come in and take a closer look. Call Allbritten here in Fresno and the Central Valley. We’ll send one of our experienced, friendly techs out to your home to figure out what the problem is and how to solve it.

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