What Causes an Air Conditioner to Freeze Up?

Is your Air Conditioner freezing up? How can something that works around the clock during the hottest months of summer to cool our indoor spaces be susceptible to freezing?

It almost seems ironic that an AC could freeze up, especially in the summer period in Kirkland, WA, where it’s pretty hot outdoors (and even indoors). Just when you need your AC the most, it freezes over, leaving you with a malfunctioning air conditioner and an uncomfortably warm home.

There are many reasons why your AC could malfunction. Unfortunately, not many homeowners are equipped with an understanding of freezing ACs and how to prevent such an issue on their own. It’s a problem that can turn a thrilling summer into a sweltering season in mere minutes.

First, let’s highlight the main consequence of a frozen AC.

A Frozen AC Will Not Cool Your Home

Exactly as it sounds, a frozen air conditioner is not good news. In fact, it’s terrible news! Your AC simply won’t function normally. If you let the issue persist, it can also damage your entire HVAC system.

Ice, as you well might know, expands when heated. And when it accumulates on your HVAC’s internal components, it can expand to burst them. If you don’t catch the issue early enough, your house won’t just be warm and uncomfortable; you will be facing a costly repair.

Understanding the Joule Thompson Effect: How Your AC Freezes Up

Before we dive into the causes of an Air Conditioner freezing up, let’s discuss a little bit about how your AC runs first.

So, stick around for a small physics lesson. After all, the key to understanding this principle is vital to understanding why your AC is malfunctioning.

The Joule Thompson Effect is a basic rule in thermodynamics, which states that if everything remains constant, as the gas expands, its temperature increases and its pressure also increases. Similarly, as a gas is compressed, its temperature will rise.

This is because what we feel as the temperature is only really a measurement of the level of energy a molecule has. Simply put, if air molecules are moving around sluggishly, then you will sense the air as cold. If air molecules are moving around vibrantly, then you will sense this as hot.

How exactly does this law apply in AC freezing? Simple. The role of a Central AC is to expand the refrigerant inside the evaporator coil for it to cool down. Then when it leaves the AC, it cools inside your living space and effectively drives away the warm air inside the house. However, if any component in the air conditioner malfunctions, the entire unit gets disoriented. This causes the evaporator coil to allow the refrigerant to cool abnormally, causing it to fall below freezing point and ice over.

Why Is Your Air Conditioner Freezing Up?

Now that you have a glimpse of how your AC freezes over, you can figure out why it ices up. Your air conditioner can freeze up for so many reasons, but we will only highlight the four most common reasons for an ice up.

By understanding the causes below, you can anticipate them, so you never have to endure an AC freeze. We’ve also included quick fixes in each section, so if you have a persistent AC problem, you could be able to troubleshoot it in no time. Keeping your AC in good shape will not only help it run more efficiently but also save you money on your energy costs.

1. Blocked/Insufficient Air Flow

Typically, ACs need to have a consistent flow of air so that humidity doesn’t sit on the coils and freeze over. In a mini-split air conditioning system, for instance, the AC is designed to reduce the temperature of your household by taking heat from it. If your AC doesn’t properly blow your indoor air over the evaporator coil, then this heat exchange isn’t possible. The freon that should be eliminating heat from your household is not doing its job. With time, its temperature will continue to reduce, and your AC could freeze up.

How to fix it: If your AC is malfunctioning, and you discover that your air filters are blocked, it’s likely an insufficient air problem. The first thing that you need to do is power off the AC and allow the ice to thaw. After it’s had enough time to defrost (1-3 hours), turn off the fan for about 30 minutes. Utilize this time to replace your air filter. After that, your Air Conditioner should be back to its usual self.

2. Refrigerant Leaks/ Low Refrigerant

This occurs due to low pressure inside the unit itself. The explanation is simple: now there is less Freon inside your AC, but it is still forced to expand up to the normal limit- the more the expansion, the cooler the temperature. As your AC’s coil falls below the freezing point, the moisture in your indoor air will freeze as it comes into contact with your evaporator coil, causing it to ice up.

How to fix it: Leaks require more than just a short guide to AC icing. It’s best to handle these issues with the help of a skilled professional who has experience in handling refrigerants. As you wait for the HVAC Company to show up, take the time to clean up your evaporator coil. You can help prevent costly AC problems by scheduling yearly tune-ups with HVAC professionals near your Kirkland home.

3. Mechanical Failures

Can you spot a blower that is running too long, a leak or crimp in your refrigerator lines, or a blocked filter dryer? These, too, can alter the pressure in your unit and make your air conditioner ice up.

How to fix it: Like refrigerant leaks, mechanical problems could require expert intervention. Be sure to contact an HVAC specialist to come over and inspect your AC. But if you think the repair might push you to dig deeper into your pockets, it might best to invest in a new HVAC system altogether.

4. Low Outdoor Temperature

Air conditioners are graduated to run within an ideal set of temperature thresholds. If you are operating your AC when the outdoor air is below 60 degrees, then the air pressure inside your unit will fall, and this can cause your Central Air Conditioner to freeze up. The same effect can be felt during cool summer nights. When nights are much too cold than what the ideal thresholds can allow, it can give your AC a cold blow that causes a freeze up.

How to fix it: Having a computerized thermometer can automatically get ahead of the issue by powering off the AC when temperatures hit below 60 degrees. If you can’t acquire a programmable thermometer, be on the lookout for the current temps every night and predict if it’s going to be colder than 60 degrees. If so, make sure you shut down your AC and leave your windows open to allow in the cool summer breeze.

Time to Schedule Professional AC Tune-Up Services

A freezing air conditioner can cause you all sorts of headaches, especially in Kirkland, WA, where the climate can get humid. However, you can prevent these issues from causing a frozen AC simply by scheduling a regular tune-up and maintenance. Replacing air filters as regularly as you can go a long way toward avoiding leakages, blocks, and mechanical hitches. Hiring an expert HVAC company, such as [company name], and anticipating temperature drops in summer nights, can help keep your AC in top condition. We also excel at services related to water heaters, electrical issues, and even indoor air quality assessments and trusted solutions. To learn more about how we can improve your indoor home climate comfort, call us today.