Causes and Prevention of AC Unit Freezing

You and your family rely on your AC unit to keep your home cool and comfortable throughout those hot summer months. Issues with your unit aren’t just uncomfortable — repairing them can also be costly. 

When the temperature starts rising, it can catch you off guard to find that your system froze up. Several issues can cause this malfunction — many of which are preventable. 

Discover some common causes and ways to prevent your AC from freezing up to ensure you have a functional cooling system you can depend on all summer long. 

How to Tell if Your AC Is Freezing

While the most obvious sign of an AC freezing up is ice on the refrigerant pipes, it’s also common to see a frozen evaporator coil. The evaporator coil is found behind a panel on the indoor unit. 

You may also spot earlier, more subtle signs like condensation starting to form on the surface of the indoor unit or exterior of the condensate drain. You might also notice that your AC isn’t cooling down your house as effectively as it used to. Taking stock of these small signs can help you catch potential issues early and prevent your system from completely freezing up.

7 Reasons an AC Can Freeze Up

An AC unit that isn’t regularly maintained is more likely to freeze up unexpectedly. When frost starts to build on the refrigerant lines, the exterior condenser coils and interior evaporator coils appear frozen.

These are seven common causes of an AC freezing up: 

1. Incorrect settings: Be sure to monitor your AC temperature settings, especially when the temperature drops outdoors. Depending on your AC unit and filter, it may not work correctly if it runs at a low temperature. Adjusting the temperature whenever it’s cold outside can help keep your system running as it should. 
2. Dirty air filter: If dust and dirt start to accumulate on your air filter, it will impact the airflow through your unit. If air isn’t able to pass through, the system will become overloaded, which can result in your unit freezing. 
3. Inadequate airflow: Issues like damaged air ducts or a dirty air filter can disrupt the airflow in your unit. Your AC unit needs to have a constant flow of air to work correctly. Any time there is a blockage, refrigerant condensation can start to form on the coils and then freeze. 
4. Damaged blower fan: A damaged blower fan can negatively affect the entire heating and cooling system. A faulty blower fan isn’t able to blow enough air — or any air at all — through the unit. When this happens, the coils can start to freeze up and can cause the AC unit to stop working completely. 
5. Clogged condensate drain line: Your unit’s condensate drain line is responsible for draining the condensation produced from the cooling system process. If it is clogged due to debris or dirt, the line won’t be able to drain the condensation out of your home. The drip tray may overflow and then freeze if the evaporator coil is too cold. 
6. Improper refrigerant levels: Ice can build up on your system if it’s leaking refrigerant. Similarly, whenever the levels get too low or too high, your system won’t be able to operate as it should. Incorrect levels cause reduced pressure and can make the evaporator’s temperature drop too low. Moisture will then get icy, eventually causing the unit to freeze up.
7. Damaged wiring: Electrical wiring in areas like the outside condenser unit or the furnace can become damaged. In addition to being a safety hazard, torn or burnt wiring can cause a freeze-up and lead to expensive repairs. 

How to Fix an Air Conditioner That’s Freezing Up

If you’re dealing with an air conditioner that’s freezing up, there are several things you can do to troubleshoot. The easiest fix is to simply change the air filter. Start by turning off the system so that it can defrost. Then, check the filter to ensure it’s not so dirty that it’s blocking the airflow through the system. If the filter is the culprit, a replacement will resolve the frozen system. 

Setting up a thermometer and monitoring and adjusting your temperature settings as needed can also help resolve a frozen system. It’s best to turn off the AC whenever the temperature drops below 60 degrees. More involved issues are best left in the hands of a trained professional. 

How to Prevent Your AC Unit From Freezing 

Because dirty filters can impact how well your AC unit works, one of the easiest ways to prevent it from freezing is to change your filters regularly. Several factors help determine how frequently you should change them, ranging from how many people and pets live in your home to the type of air filter your system uses. On average, it’s recommended to change your filter every 90 days to ensure proper airflow through the system. 

Another simple way to prevent your unit from freezing is to schedule annual maintenance with an HVAC professional. They will thoroughly evaluate your system, look for potential airflow issues and make repairs as needed. From checking the ductwork for proper airflow to cleaning away dirt and grime from the coils, they’ll make sure everything is good to go. 

When to Call a Professional

While there are several things you can check on your own, your AC is still a complex system. If you’ve changed your air filter and are still dealing with a frozen system, something else is probably going on that will require professional troubleshooting and service. 

Your filter may be wet, or there may be a dirty coil in your system. It’s also possible that your system is experiencing a refrigerant leak or something is causing a clog in the ductwork. It’s best to leave these kinds of issues and repairs to a qualified HVAC technician. 

Keep Your AC Running the Way It Should

If your home AC is freezing up, turn to the experts at HB Home Service Team. Since 1914, we’ve been providing professional HVAC, plumbing and electrical services to homeowners throughout Central Pennsylvania. Our team is committed to delivering full-service solutions and outstanding results for your residential needs. 

Our team will come out and inspect each part of your AC system to ensure you and your family stay cool and comfortable all summer long. Along with AC repairs, we also provide regular maintenance services to make sure your system is ready for those hot summer days. Our maintenance services are designed to prevent unexpected breakdowns or costly repairs. With our large team of technicians and competitive pricing, you can expect responsive, high-quality work that fits your budget each and every time.

Give us a call at 717-232-4328 or reach out online today to receive an estimate or schedule an AC service.