Why Is My HVAC’s Evaporator Coil Frozen and What Should I Do About It?

Have you ever noticed ice building up on your HVAC system? If so, there’s a good chance your evaporator coil is frozen. At Max Air, we get a lot of calls from homeowners wondering why this is happening, if it’s dangerous, and what they can do to fix it. The good news is, you're not alone. The bad news? A frozen coil isn’t something you should ignore.

Let’s walk you through what an evaporator coil does, why it might freeze, and the safest steps you can take to get your AC working again.

First, What Does an Evaporator Coil Do?

Your evaporator coil is one of the key components inside your HVAC system. It’s usually located near your air handler (the indoor unit) and is responsible for absorbing heat and humidity from the air in your home. The coil contains refrigerant, which cools the air as it passes over the coil before sending it through your ducts and into your living space.

When everything is working correctly, your home stays cool and comfortable. But when the coil gets too cold, it can literally freeze over, and that’s a sign something’s wrong.

Why Do Evaporator Coils Freeze Up?

A frozen coil can be caused by a few different issues. Understanding the possible reasons can help you avoid more damage and know when it’s time to call in a professional.

One of the most common causes is restricted airflow. When warm air can’t move over the coil like it’s supposed to, the coil’s temperature drops too low and ice begins to form. Here are a few things that can cause poor airflow:

• Dirty air filters: Clogged filters reduce the amount of air reaching the coil.

• Blocked or closed vents: Furniture, rugs, or closed registers can prevent air from circulating properly.

• Dirty evaporator coil: Dust and debris can insulate the coil, making it harder to absorb heat.

• Obstructed return ducts: If your system can’t pull in enough air, the coil gets too cold.

If airflow isn't the issue, refrigerant might be the problem. When your system is low on refrigerant, the pressure inside the coil drops. This causes the temperature to fall below freezing, leading to ice buildup. Electrical or thermostat malfunctions and extremely dirty coils can also contribute to the problem.

No matter the cause, the outcome is the same: your system isn’t working efficiently, and continued operation could make the damage worse.

Is a Frozen Coil a Serious Problem?

Yes, it's not something you want to brush off. A frozen evaporator coil is more than just an inconvenience. It’s a warning sign that your HVAC system is under stress and could be at risk of more significant (and costly) damage.

If you keep running your system while the coil is frozen:

• The compressor, which is the heart of your AC system, can become overworked and eventually fail.

• Your air conditioner will lose efficiency, meaning higher energy bills with less cooling.

• As the ice melts, excess water can overflow the drain pan and cause water damage to your home.

That’s why it’s so important to take action quickly. But make sure it’s the right type of action.

What Should You Do If You Notice Ice?

First, turn your HVAC system off. Running it while the coil is frozen won’t solve anything and will only put more strain on your equipment.

Next, follow these steps:

1. Turn off the system completely at the thermostat and breaker to let the coil start thawing naturally.

2. Check your air filter and replace it if it’s dirty. A clean filter helps maintain proper airflow, which can prevent freezing in the future.

3. Let the ice melt on its own. This might take a few hours. Do not use a hair dryer, space heater, or any tools to melt or chip away the ice. This can cause physical damage to the coil or even lead to electrical hazards.

After the coil has thawed, resist the urge to immediately turn the system back on. At this point, the best thing you can do is call a professional HVAC technician to diagnose the underlying issue.

Avoid the DIY Hacks

We know the internet is full of “quick fix” tutorials, but when it comes to frozen coils, trying to fix the problem yourself can do more harm than good. Hacks like pouring hot water on the coil, manually adding refrigerant, or tampering with internal components could void your HVAC system warranty, cause injury to yourself or damage to the unit, or delay a real repair, making the problem worse.

In other words, DIY fixes might seem like a cost-saving hack, but they can end up costing you more in the long run.

Call Max Air To Get Back to Comfort

At Max Air, we help Maryland homeowners like you stay comfortable year-round. If your evaporator coil is frozen, we’ll get to the root of the issue. Our experienced technicians will perform a full inspection and make sure your system is running efficiently and safely again.

Don’t let a frozen coil ruin your summer. Call Max Air today or schedule service online.