What Are AC Coils and Why Do They Matter?
Coils keep your home cool and comfortable
Highlights
There are two kinds of AC coils: evaporator coils and condenser coils.
Evaporator coils are in the indoor part of your AC unit and absorb heat.
Condenser coils are outside and release the heat from the evaporator coils.
You also have an AC valve to control the amount of refrigerant in your system.
Each of these parts works together to cool your home.
It may be sweltering outside, but thanks to your AC coils, you’d hardly even know it from inside your house. You might not be familiar with what they do, but these hard-working heroes of your HVAC system make your home a whole lot more comfortable—even on the hottest days of summer. So, what are AC coils, and how do they work? Let’s break down the different types and explain how they partner up with AC valves to cool your home.
What Are AC Coils?
Air conditioner systems have two types of AC coils: evaporator coils and condenser coils. As a brief overview, these coils work together to get rid of hot air from inside your home by absorbing it into refrigerant and then transferring that heat outside.
What Is an Evaporator Coil?
Evaporator coils sit within the indoor part of your AC unit and are typically made from aluminum, steel, or copper. Their job is fairly simple: Get warm air outside of your home.
Here’s how an evaporator coil works:
Your blower pushes hot air from inside your home over the coil.
The refrigerant in your evaporator coil absorbs the heat and transports it outside to the condenser coil.
What Is a Condenser Coil?
Condenser coils are located outdoors in your AC’s condenser unit. They receive the refrigerant—which, as a reminder, has absorbed the heat from your indoor air—from your evaporator coil before eventually releasing the warmed air into the atmosphere.
Here’s a more in-depth explanation of how condenser coils work:
After the refrigerant absorbs heat from your indoor air, it exits the evaporator coil through a copper tube and enters your condenser unit.
Warm refrigerant gas goes into the compressor, which pressurizes it and transforms it into a hot gas.
Your condenser coil converts the gas into a liquid, pushing the heat from the refrigerant outside.
Now in liquid form, the refrigerant returns to the evaporator coil and begins the cycle again.
What Is an Air Conditioner Valve?
Your AC unit also has a valve that regulates the flow of refrigerant throughout the HVAC system. Also known as an expansion valve, this device sits in front of the evaporator coil, opening and closing to allow refrigerant into the evaporator.
On high-efficiency AC systems, there’s an even more sophisticated AC valve—called a thermostatic expansion valve (TXV)—that allows a precise amount of refrigerant through based on how much your system needs at that time. You might wonder: Why does this matter? When your AC unit has too much or too little refrigerant, it can impact its efficiency. So, by providing just the right amount, a TXV helps your HVAC system hit an operational sweet spot.
The Importance of AC Coils and Valves
Working together with the compressor, AC coils and valves move hot, stuffy air outside your home, making it feel cooler and more comfortable. When each of these HVAC system parts operates smoothly, they improve the efficiency of your entire system.
Importantly, an expansion valve on AC helps ensure that the right amount of refrigerant gets into your system. If there’s too much refrigerant in your system, it can lead to all kinds of problems, including:
Lukewarm air lingering in your home
An inefficient HVAC system that runs constantly
A damaged compressor
Maintaining Your AC Coils and Valves
Like other parts of an HVAC system, AC coils and valves can collect dirt, dust, and debris—and since they contain refrigerant, they can also leak. Fortunately, cleaning your AC coils once per year (in addition to scheduling an annual air conditioner servicing) may help prevent these problems. You can tackle this job for less than $10 if you have the right tools.
However, whenever you clean your AC coils, there’s a risk of damaging the delicate coils or fins, which are expensive to repair. If you don’t want to perform this task yourself, contact a local heating and cooling company. As experts in all things HVAC, these pros know the right way to clean your coils without damaging them. They typically charge between $100 and $400 for the job. Plus, during their visit, they can check out the rest of your HVAC system to identify any current or future issues.
By keeping up with regular HVAC maintenance, you’ll help your AC unit run more efficiently and possibly extend its life span. Plus, you’ll reduce the likelihood of expensive problems down the line.
Frequently Asked Questions
On average, the cost to replace an evaporator coil is between $600 and $2,500, with most people paying around $1,350. Costs depend on the brand and size of the unit, as well as the style of the evaporator coil. If you need a new condenser coil, it usually costs around $800.
If you don’t clean your AC coils, dirt and debris build up inside your unit, making transferring heat more difficult. As a result, your HVAC system will work harder to run, potentially increasing your energy usage and utility bills. Neglected coils may also become corroded, which can lead to refrigerant leaks and mold growth—both of which can cause a slew of negative health impacts.
Evaporator coils last between 10 and 15 years before they need to be replaced—as long as you stay up-to-date with routine maintenance. This is roughly the same life span as most AC units. So, if you have an older air conditioner and the evaporator coil goes out, it might be more cost-effective to replace the whole unit rather than just the coil.