Frozen Air Conditioner

AC Frozen

It can be alarming to discover a block of ice in your AC. Luckily, it’s not as scary as it looks.

Air conditioners freezing over is actually a common problem. Sometimes a frozen AC requires professional help, but you may be able to repair it yourself depending on the cause of the freeze.

How to Fix a Frozen AC

The only way to remove ice from your air conditioner is to shut it off and allow the ice time to melt.

When your air conditioner is on, it is pumping freon through the evaporator coils, which means they’re going to stay cold and the ice won’t melt. You can turn your system off, or you can set it to the “FAN” option. If your system does have the fan only option, use that. It will help the evaporator coils dry off faster. It should take about 24 hours for the ice to melt, but it could be longer if it’s a solid block of ice.

While the ice is melting, you’ll want to keep an eye on your condensate drip pan. If your thermostat does not have a fan only option, you should take a towel or paper towels and dry off the evaporator coils and fins. If you have the fan only option, you shouldn’t have to do anything other than leaving it blowing for 24 to 48 hours.

What Causes Your Air Conditioner to Freeze Over?

One of your air conditioner’s jobs is to dehumidify your home. That means it sucks water out of the air to make the air inside your home drier.

Your air conditioner pumps freon from your condenser outside through the evaporator coils, which are the metals frames inside your AC unit. The water in the air is sucked onto these cold metal coils and becomes condensation when the air passes over them. Usually, when your air conditioner is continually running, water collects on your AC’s evaporator coils. The water is supposed to drip off the coils and dry, however, if the water stays on the cold coils for too long it will turn into ice.

Below are things that can impede the process outlined above and cause your air conditioner to freeze.

1. Decreased Airflow/Clogged Air Filter

Dirty air filters can cause your air conditioner to freeze by decreasing the amount of air going through your system. Your AC is designed to work with a specific balance of airflow and pressure. Just the right amount of water has to collect on the fins, for the perfect amount of air to pass over it, so the drops drip just right into the condensation drip pan.

One slight change to this equation, such as less air passing over the fins because less air can get through your clogged filter, can completely throw off your AC’s balance. When there isn’t enough air passing over the fins, the water droplets hang out on the metal for a little bit too long and turn into frost.

2. Low Refrigerant Levels

Another common cause of freezing is the refrigerant level being too low. Freon is another name for the refrigerant used to cool the evaporator coils in your AC. As a chemical, it is very sensitive and can change states of matter very quickly. For example, freon could be a liquid that is boiling or not boiling at the same temperature, depending on pressure. The pressure inside of your AC is determined by airflow.

If any part from your compressor to your inside unit is obstructing airflow, or changing the temperature of the system, then this delicate balance can be thrown off. During normal operation of your AC system, your condenser holds the freon as gas. Your compressor makes this freon super hot, at 100 degrees Fahrenheit the chemical turns from a gas into a liquid. When anything is extremely hot, it also has a high pressure. So your AC system shoots this high pressure, liquid hot freon towards your house. Before the hot liquid freon reaches the inside part of your AC system, it’s pushed through a special device that makes it incredibly cold, around 20 degrees Fahrenheit, very quickly.

When refrigerant levels are too low, that means that the pressure inside of the tubes the freon travels through will also be too low. When the pressure is low, the freon is colder than usual when it gets to the cooling stage just before being run through your evaporator coils. This makes the evaporator coils extra cold and can cause the water to freeze. Measuring the pressure and the level of refrigerant in your system takes some special tools, so it’s best to leave that to the professionals.

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3. Fan Problems

Another common reason for AC freezes can be an issue with your fan. That might sound concerning, but don’t worry. Fans can get dinged or worn out through normal use and operation. Sometimes a larger object travels through your system and it can knock the AC fan out of balance.

An HVAC professional will be able to tell you if your fan is running properly, and get it back to spinning level.

4. Dirty Evaporator Coils

Your air conditioner filters all kinds of gross stuff out of your home’s air, such as hair, pet dander, dust, dirt, and mold. But your AC filter doesn’t catch everything, so over time the evaporator coils inside your system can become caked in layers of grime. You can call a friendly Blair’s Air licensed HVAC professional to do a deep cleaning, which you might need to do depending on how bad the dirt is. Otherwise, you can try to remove some of the gunk yourself.

First, be sure to turn the air conditioner OFF. Some people recommend switching the breaker to the system off as well. You can use a soft brush like a toilet brush or a toothbrush to scrub buildup off of your evaporator coils. You could also use a paper towel, and gently try to loosen the grime on the fins with your hand. Be careful not to use too much pressure, you don’t want to bend any of the metal fins or coils.

The professionals at Blair’s Air use special chemicals to loosen more intense buildup, but if you have minor grime you can try to use some water to loosen it, then scrub it off with a soft brush or a paper towel.

Call Blair’s Air, the Best Air Conditioning Team in Tampa Bay

If you have tried these remedies and your AC is still freezing, you may need the help of a professional. Luckily these are not major, or expensive repairs, but they are generally a little too complicated for the DIYer to handle.

Woke up to a glacier in your AC? Don’t sweat. You can get immediate support from one of our friendly, licensed HVAC technicians in Tampa, St. Petersburg, Pinellas, or Hillsborough. Just give us a call or easily schedule a service online.

Call (727) 800-4148 to schedule your appointment.

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