Here in the Atlanta metro area, air conditioning is essential to make it through the summer. So, if your AC freezes up and stops cooling your home, it’s easy to assume the worst. However, there are a variety of things that might cause your AC to freeze, and not all of them are difficult to fix. Here are some of the most common reasons that your AC might freeze and what to do if it happens.

A Dirty or Obstructed Air Filter

Poor airflow around your AC evaporator coils is one of the most common causes of AC freezing. And one of the most common causes of airflow problems is a dirty or obstructed AC air filter. When your air filter gets dirty and isn’t changed on schedule, it will begin restricting the return airflow through your AC system. This means that the warm air from your home won’t reach the cold coils of the evaporator, allowing it to freeze. If your AC has this problem, however, don’t worry. All you have to do is change the filter, and the problem should go away.

Too Many Closed or Blocked Vents

Your AC could also freeze if you don’t allow cold air to exit the system’s ductwork via the vents in your home. This often happens when you close too many vents to alter the flow of cool air in certain rooms. If you go too far, you’ll create an increase in the static pressure inside your ductwork that your AC’s blower motor can’t overcome. That will keep cold air closer to your evaporator coils and cause them to freeze up. This is another issue with a simple solution. Just open up the vents throughout your home to restore your AC’s airflow balance, and it should solve your problem.

A Clogged Condensate Line

If you stop to think about it, it should be obvious that freezing problems must involve water. This is exactly why your AC system has a condensate drain line meant to carry water away from your evaporator coils to prevent freezing. However, when that drain line gets clogged, it can’t do its job, and your AC might freeze up.

As a homeowner, this isn’t the easiest problem to spot once your AC freezes. The key is to keep an eye on your AC before that happens. On most days, you should see a steady drip coming from the outlet of your AC’s condensate drain line as it runs. If you don’t see that, you might have a clog and will need a professional HVAC technician to sort it out for you.

Your System Needs Refrigerant

As odd as it might sound, your AC could freeze if it runs low on refrigerant. This happens because your closed refrigerant system can’t maintain the right pressure, leading to excessive moisture buildup on your evaporator coil. Most of the time, you’ll get some warnings of a refrigerant issue in your AC before it freezes. Your first sign of trouble might be cool, but not cold, air coming from your vents. Or it might begin taking much longer than normal to cool down your home.

However, this is another problem that you can’t solve on your own. You’ll need a professional AC technician to test your system’s refrigerant pressure and locate any leaks that led to abnormal refrigerant loss. Then, after they fix any problems, they can recharge your AC and restore it to normal operation.

Your Thermostat’s Malfunctioning

A malfunctioning thermostat could also be the culprit if your AC freezes. This can happen when your thermostat isn’t sensing the indoor temperature correctly or isn’t telling your AC to shut off when it should. In either case, your AC would run for much longer than necessary, dropping the air temperature lower than it should and allowing the evaporator coils to freeze.

One way you can check to see if your thermostat’s malfunctioning is to place a thermometer near it. If the two temperature readings don’t match, your thermostat could have a problem. When this happens, it’s possible that the thermostat just needs recalibration, but it’s more likely you’ll need a new thermostat to solve your freezing problem.

How to Deal With a Frozen AC

The most important thing to do when your AC freezes is to turn it off. When your evaporator coils freeze, they will prevent air from passing through your AC system. That will put an enormous strain on your blower motor. If you leave your AC running with a frozen coil for too long, it might shorten the blower motor’s lifespan.

The good news is that defrosting your AC shouldn’t take too long, especially on a hot day. In most cases, you’ll only need to leave your AC off for an hour or two. You can use the time to look for signs of what’s causing the freezing while you wait. If you’re lucky and your problem is a dirty air filter or too many closed vents, your AC shouldn’t be out of commission for too long.

However, if you didn’t notice the problem right away, it could take as many as 24 hours to defrost your evaporator coils with your AC off. If you can’t wait that long, though, there are a few ways you could speed up the process. If you can access your AC’s evaporator coils through a nearby service access door, you could use a hairdryer to melt the ice. To do this, you should keep the hairdryer about 10 inches from the coils and continue blowing hot air on the coils until there’s no more ice visible. The process should take around 15 minutes.

If you can’t access the evaporator coils, your only other option is to turn your AC system’s fan on via its control switch on your thermostat. This will engage the fan without turning on your AC’s compressor. Doing so will blow warm air from your home across the frozen coils to melt the ice. However, this should be your option of last resort since you will be straining your blower fan in the process.

While your AC defrosts, you should feel a bit of cool air coming from the vents in your home. You’ll know that your coils have defrosted when the air coming from the vents is lukewarm. At that point, you can turn your AC back on to see if it’s working normally.

Your AC Repair Specialists

Since 1985, Precision Heating & Air has offered quality HVAC services to homeowners in Dallas, GA and the whole Atlanta metropolitan area. With over 60 years of combined experience on our team, our NATE-certified HVAC technicians can handle all of your HVAC installation, repair, and maintenance needs. We also offer indoor air quality services, dehumidifiers, and water heaters. Plus, we offer 24/7 emergency services, so you won’t have to wait for the HVAC help you need. If your AC keeps freezing or you have any other HVAC problem, call the experts at Precision Heating & Air today!

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