In the warmest season of the year, it seems crazy: you step outside, do a double-take, and wonder, “Why is there ice on my HVAC unit?”

This issue can crop up any time of the year, but it seems most baffling in the peak of summertime. Ice can form on your HVAC unit for a number of reasons, but all of them are serious enough to warrant further inspection. Leaving ice to develop on your unit can waste energy, raise your utility bills, and even cause a total system failure.

Fortunately, regular DIY maintenance and professional HVAC checkups can help lower the risk of this happening.

Unfortunately, even if you do everything correctly, you might still find yourself with AC unit frost—as luck would have it—in the middle of a heatwave.

Why does ice form on your HVAC, and what should you do if it happens? Here are a few common culprits to check for.

Low Refrigerant

When your air conditioner is working properly, air passes over your system’s evaporator coil. Condensation forms as a result, removing moisture from the air. This moisture drips safely away into a drain pan.

However, when your HVAC system is leaking refrigerant, it means there’s less refrigerant inside your system where it belongs. And because there’s less refrigerant inside your coil, it has more room to expand, growing colder and colder. In time, this expansion can cause ice to form on your coil, which in turn can freeze your system.

Because refrigerant can be a hazardous substance—in addition to your existing issue of a frosted HVAC system—it’s important to have the problem taken care of as soon as possible.

Solution: Check around your HVAC unit for any signs of a leak. If you find one, you’ll need to have an expert come out and seal the leak before you add any new refrigerant.

Wiring Issue

If you notice that your air conditioner cycles on but never cycles off—even after the house has reached the temperature you’ve set on your thermostat—it might be an issue with your wiring. And because your HVAC system is running nonstop, ice may develop as your compressor keeps working even after the fan stops.

Solution: An HVAC specialist should check for and diagnose any problems with the electrical components of your system.

Low Airflow

Your evaporator coil is designed to absorb the heat that comes from your home’s air. As long as your home’s air filter is unclogged, there’s enough airflow to keep the system running smoothly.

However, if the air filter grows too dirty, it can prevent enough air from blowing over your evaporator coil—one of the most common HVAC problems homeowners deal with.

As a result, none of your home’s heat is absorbed into the coil. In turn, the area will get warmer and warmer, and the coil will get colder and colder, expanding a little more as your AC cycles on and off. The end result is your HVAC frosting over.

Solution: Make sure you follow manufacturer guidelines and change your air filter at least once a month. Don’t forget to use a quality air filter to keep your air flowing smoothly.

Dirty Evaporator Coil

It may seem strange that a little dust can shut down your HVAC system, but a dirty evaporator coil may be the culprit at hand. Like the air filter issue above, a dirty evaporator coil restricts airflow throughout your unit, which can cause the coil to freeze over time. It can also cause lasting damage to the compressor if your HVAC system is allowed to continue running.

Solution: Check for any dirt or debris that may be acting as insulation around your evaporator coil. Clear away any buildup. Call for a technician to check for lasting damage.

Mechanical Failure

There are a number of other issues that may lead to your air conditioner frosting over, including broken valves, dented refrigerant lines, damage to your blower fan, or a blocked drainage system.

Solution: These can be a little harder to identify, but a licensed HVAC technician will be able to take a look for these more subtle issues.

What Steps Should I Take to Check for Ice on My HVAC Unit?

If you’re not sure which of these issues is to blame for your AC unit frosting over, don’t panic. Some of these problems are tricky for homeowners to diagnose, but an HVAC technician will be able to identify and solve the underlying cause of your frozen HVAC system.

Here are a few steps to take as soon as you notice any sign of ice or frost on your air conditioner.

First, shut the system off using your thermostat. This gives your air conditioner a little time to defrost while you check to see what’s wrong.

Before you get too far into problem-solving, change the air filter. If the frost is simply the result of a dirty filter, as mentioned above, this will be a quick fix. You should also make sure there’s nothing else blocking the airflow around your vents, like window treatments or furniture.

Next, check for refrigerant leaks, clean the evaporator coil, and look for any other signs of damage to your unit.

If you’re still not sure of the cause, you should try to document all of the potential issues you notice.

Is there ice inside your AC unit as well? If so, you might notice an overfull drip pan, which can be a red flag that there’s ice melting in your AC system. Otherwise, you might hear strange noises from the system, especially bits of ice falling (a sound similar to the one a refrigerator makes as it defrosts).

Is your HVAC system constantly cycling, or is shutting off almost as soon as it cycles on? Is hot air blowing into your house, or is there no airflow?

Describe the issue in full when you reach out to an air conditioner specialist. Having a better picture of your unit’s symptoms can help them diagnose the problem or think about potential causes before they arrive.

Why Is There Ice on My HVAC Unit?

If you’ve done your best to check for the issues above and you’re still coming up empty, or if you know the cause but not how to fix it, it may be time for the next step. Stop wondering “Why is there ice on my HVAC unit?” and call for backup!

Contact us when you need immediate service. We’ll get your air conditioner back to keeping you and your family cool in no time.