Why Do Air Conditioners Freeze Up?

Frozen AC Unit On Roof

We know what you’re thinking: If an air conditioner is designed to blow out cold or freezing air, is it really a big deal when the unit itself becomes frozen? 

Unfortunately, yes. 

When your air conditioner freezes up, it prevents the unit from moderating temperatures in your home. It can even prevent the unit from blowing in any air at all. When left unattended, a frozen air conditioner will stop working and can lead to more significant structural damage to your AC unit. 

Below, we’ll discuss why air conditioners freeze up, what to do about it, and how to prevent a freeze from occurring. 

How Air Conditioners Work 

We’ve come a long way since the first air conditioner was invented in the early 1900s. Though the original AC model came out over 100 years ago, most AC units still work under the same general principles.  

Before we can understand why air conditioners freeze over, we first must understand how the mechanics work.

There are four main components at work in your AC unit. They are: 

  • The compressor
  • Condenser coil
  • Evaporator coil
  • Refrigerant

There are two processes at work when your air conditioner moderates your indoor temperatures. The first is that the air conditioner removes hot and humid air from your home and pushes the hotter air outside. 

How does it do this? A cooling liquid called refrigerant absorbs the hotter temperatures and moves them back through your unit until it ejects them outside.

The AC unit produces cool temperatures by using the compressor, condenser coil, and evaporator coil to convert the refrigerant from a liquid into a gas. This now cooler, gaseous air is transferred into your home to lower your indoor temperature. 

Sound confusing? We admit, it’s a rather complicated system. More simply put, your AC must allow warm air to circulate within the unit so that the coils don’t become too cold and can continue to work properly. 

Why Do AC Units Freeze? 

A frozen AC unit happens when a problem occurs with the coils. If the coils become too cold, they can freeze up. But why would coils become too cold? 

More often than not, there’s a lack of airflow within your HVAC system that prevents warm air from flowing over the coils. But there are other reasons why your AC unit might freeze, such as excessive moisture and humidity or low refrigerant levels. 

Clogged Air Filters  

Poor airflow is a top reason why AC units freeze over. Again, when there is a lack of warm airflow over your coils, the coils become too cold. 

Several factors contribute to poor or weak airflow. One of the most common is a clogged air filter. 

Though your HVAC air filters are perhaps the easiest mechanism in your HVAC unit to clean and change, many homeowners underestimate just how important a properly functioning air filter is to the overall health of their AC unit. 

When your air filter is clean, it adequately stops dust and dirt from entering your ducts and getting blown into your AC unit. However, when the air filter clogs with dust, it restricts airflow. As a result, warm air cannot pass over your AC coils, and the AC unit can freeze. 

Excess Humidity 

Humidity levels play a key role in how well your AC unit functions. When there is too much moisture in the air, your AC unit has a harder time, because excess moisture can create ice buildup. 

When ice collects, it can act as a blockade and prevent warmer air from reaching the AC coils. 

Low Refrigerant Levels

Refrigerant levels are crucial for a successfully operating AC unit. When your refrigerant is low, the pressure in your AC unit is off, thereby causing ice to build up in your compressor. 

Damaged Air Ducts 

As you probably know, your air duct is the system that allows air to flow from your AC unit into your home and back to your AC unit again. 

If your air ducts are bent, have leaks, or are damaged in any way, the airflow is simply not as strong as it needs to be. As a result, hot air has difficulty flowing over your coils. 

Low Voltage 

Never underestimate the power of electricity. 

Electricity plays a vital role in your AC’s operation as it is the power source behind the fan and blower. If there’s something awry with your electricity, the fan and blower won’t blow hot air over your AC coils even though the system is continually running. 

What does this mean? Over time, your coils will run too cold, and eventually, your unit will accumulate too much ice. When this happens, it’s imperative to call a team of local professionals to fix this problem as soon as possible. 

How to Prevent a Frozen AC Unit 

Perhaps the greatest tool homeowners in Charleston, SC, can use to prevent a frozen AC unit is the ability to schedule routine maintenance and service. 

When you schedule routine air conditioning service, you allow a professional technician to inspect your unit. Routine inspection gives you and your local technicians a heads-up on failing parts or low refrigerant levels. 

Additionally, during a routine maintenance check-up, our technicians will thoroughly clean your filters, air ducts, and more to prevent any blockages that might lead to a frozen AC unit. 

If your AC unit has a history of freezing, you may also want to schedule preventive maintenance before that humid Charleston, SC, summer begins. 

Call Max’s Fix-it 24/7 Heating & Air Today 

At Max’s Fix-it 24/7 Heating & Air, we leverage our impressive 20 years of experience to bring you only the best air conditioning service and maintenance in Charleston, SC, and the surrounding area. 

We’re dedicated to delivering top-tier work every time, and we guarantee that you’ll be satisfied with our local professionals and air conditioning services. 

Call us to schedule your next air conditioning service appointment, and see why we’re the most trusted AC local professionals in Charleson, SC. Give us a call today!

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