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5 Reasons Why Your AC Is Freezing Up

If you ever find your AC unit frozen, you may wonder how something that works its hardest during the hottest days of the year could possibly freeze up. Despite the irony in an AC freezing up during the summertime, it’s important to deal with your frozen AC unit properly and quickly to prevent any serious issues from occurring.

Believe it or not, an air conditioner freezing up isn’t an uncommon issue. Nevertheless, few homeowners have a good understanding of why their AC unit freezes up or how to deal with an air conditioner freezing up, so this blog will serve to bring some clarity to the situation. We'll explore in detail the 5 reasons why your AC is freezing up:

  1. Malfunctioning thermostat
  2. Lack of airflow
  3. Low refrigerant levels
  4. Blocked condensate line
  5. Dusty coils

 

How an Air Conditioner Unit Works

Before you can clearly understand why an air conditioner freezes up, it’s helpful to understand a little bit about how your AC unit works. Simply, an air conditioner in a central heating and cooling system works by drawing in warm air, removing its heat using refrigerant coils, and then providing cool air through the home through the ductwork in the home. 

For this process to work properly, an AC unit relies heavily on its coils that are full of refrigerant. When the warm air is blown across these coils, the coils cool the air and blow the cold air into the home while blowing any warm air outward. This process works to cool your home and keep it comfortable in the summertime, but the warm air blowing across the coils also helps you not find your air conditioner frozen over.

If something were to prevent the warm air from blowing over the coils, however, or if the pressure within the coils is wrong, they can become far too cold to operate. What results is your air conditioner freezing up. Before you’re too tempted to get into your AC unit yourself trying to find out what’s wrong, let’s examine a few of the most common reasons why an AC unit freezes. 

5 Reasons Why Your AC is Freezing Up

1. Malfunctioning Thermostat

So you’ve found your air conditioner frozen, and you’re wondering if it’s a serious issue. The first thing you should check is your thermostat since it could be causing your AC unit to work too hard, leading the machine to run too long and cause the coils to freeze over simply due to overwork. Checking your thermostat settings is actually one of the first things you should do to troubleshoot a variety of common AC unit problems.

 

2. Lack of Airflow

If the warm air can’t blow across the coils, then they will likely freeze over. That’s why lack of airflow is one of the most common reasons you’ll find your AC unit frozen. Here are a few different issues that can cause poor airflow:

Bad Motor

If the blower fan stops working properly, then the air stops flowing properly across the unit’s coils. When this happens, the coils start to freeze over. If this is the case, you may hear some rattling sounds from your AC unit indicating that the blower may be failing.

Low Fan Voltage

You may simply have a voltage issue if you find your AC unit freezing up. Without the proper electricity, your unit won’t have the power to blow air properly which could result in your AC freezing up.

Collapsed or Blocked Ductwork

In most homes, the ductwork is what allows cold air to move through the home. If something is blocking the duct, then air cannot flow, blocking the coils and causing your AC unit to freeze up even if everything else is working properly. 

Clogged Filter

When was the last time you changed your unit’s air filter? This filter is what works to keep your home, AC unit, and the compressor coils clean. If it’s clogged with dust, it can force your AC unit to work harder while also preventing proper airflow.

 

3. Low Refrigerant Levels

If you’re running low on refrigerant in your AC unit, the pressure in your coils can become negatively affected. As mentioned earlier, if the pressure within the coils is off, they can’t do their job properly which can cause the AC unit to freeze over. This could simply mean that you need to refill your refrigerant, or it could mean you have a more serious issue: a coolant leak.

A coolant leak causes a consistent lack of pressure, reducing your unit's ability to absorb heat which, as we know, causes it to freeze up. While you can attempt to add more refrigerant to your system, a leak needs to be addressed by a professional so it can be properly repaired. Consider getting a cooling inspection to determine the cause of your refrigerant issues.

 

4. Blocked Condensate Line

The condensate lines work to allow moisture buildup to drain from your unit (preventing it from freezing up). It’s possible for these lines to become clogged, causing the water to freeze up, which in turn causes the coils to do the same.

 

5. Dusty Coils

If you’ve ever run your AC unit without a filter, with a low-quality filter, or without changing the filter properly for a long period of time, dust can end up in the refrigerant coils and build up. Overtime, this leads to a blanket of dust on the coils, insulating them, and ultimately leading to the problem of freezing up.

 

Keep Your Air Conditioner Healthy All Summer

If you’re dealing with your air conditioner freezing up and don’t know the proper way to address the issue or to prevent it from happening in the future, then John C. Flood is ready to help resolve the issue. Whether it’s a quick cleaning needed or an in-depth repair, our licensed HVAC technicians are ready to help you keep your AC unit happy and healthy all summer long.