What Causes an AC Unit To Freeze Up, and How Can It Be Fixed?

Imagine you’re in the middle of a summer heat wave in the San Francisco Bay Area. Temperatures have hit over 100 degrees, and your air conditioner has stopped working. When you open it up, you’re surprised to find ice inside. 

If your AC unit is freezing up, don’t panic! This is a common problem many households deal with at some point. There are a few reasons ice forms inside an air conditioner. Some are quick fixes, while others require a more in-depth AC repair call.

Trio Heating and Air offers emergency AC repair and other HVAC repair services. We’ll be there as soon as possible to assess the situation and fix the cause of your frozen AC. Read on to learn more about freezing AC units and when to call a professional for help.

Why Is My AC Unit Freezing Up?

To understand why an air conditioner freezes, you first need to know how an AC works. Air conditioners collect heat and humidity from your house and transfer it outside. It’s a process based on the principle that certain gasses change temperature when compressed and expanded.

Your AC has several components, including a fan, compressor, refrigerant liquid, evaporator coil, and condenser coil. These work together to blow indoor air across a cold evaporator coil, which cools the air. Hot evaporated air is sent outside to the condenser, while colder air is sent back into the house. 

The process requires good airflow and the right amount of refrigerant. If either of these is compromised, the temperatures near the condenser coil or evaporator drop drastically, causing water vapor inside the air conditioner to freeze. Without appropriate airflow and refrigerant levels, your AC freezes up.

Some of the most common air conditioner freezing causes include: 

• Mechanical failures: A failing fan motor, broken valves, or bad wiring may cause ice to form inside the AC, leading to further damage.
• Dirty evaporator coil: Evaporator coils become covered in dirt, hair, and other household debris. This eventually blocks airflow inside the AC, causing the coil to freeze. 
• Clogged condenser coil: Your AC’s outdoor portion should be kept free of leaves, grass, and dirt. A dirty condenser coil reduces the ability for warm air to blow through the evaporator coil, which stops the refrigerant from becoming warm gas. Instead, it freezes inside the AC.
• Low refrigerant: Pinhole leaks or improper refrigerant charging usually result in low pressure in the coils, which lowers the refrigerant temperature. The temperature gets cold enough to freeze any moisture in the air and causes ice buildup.

Can a Dirty Air Filter Cause My AC to Freeze?

Yes. A dirty air filter restricts the airflow in your air conditioner. It’s one of the most common reasons for ice buildup. 

The evaporator coil needs a healthy air flow to absorb heat from the air blowing through your AC. When this warm air becomes restricted, the coil freezes. The good news is you don’t necessarily need an AC repair person to check your filters. If you like DIY projects, changing your AC filter is a job you can handle yourself.

What Should I Do if My Air Conditioner Freezes Up? 

If you see ice in your air conditioner or it isn’t working as well as it used to, contact Trio. We’re your local experts in all AC services, with experienced technicians who can quickly locate and fix the problem. 

It’s best to call a pro as soon as you notice an issue rather than wait for the ice to build up. Your AC will continue to freeze until the unit is completely encased, stopping the coil from absorbing any heat. This prevents your AC from working properly and may cause it to overwork until it burns out completely.

Trust your local AC repair specialists at Trio to get your AC back in good working order and prevent further damage. 

How Can I Prevent My AC From Freezing Up? 

Here are some simple tasks you can do to prevent a residential AC repair call for a frozen AC.

Change your filters regularly 

The frequency of your AC filter changes will depend on how often you use the AC and the amount of dust and particulates in the air. We recommend changing the filter at least once every three to six months. 

Schedule regular professional maintenance

Have an expert give your air conditioner a full once-over to make sure it’s in good working order. Schedule an annual AC maintenance call with Trio, and we’ll give your AC a full inspection, test all the components, clean and lubricate moving parts, and take care of small repairs.

Know the signs of refrigerant issues and take action quickly

Some signs you have a refrigerant problem include:

• Longer cooling cycles
• High electric bills
• Hissing sounds 
• AC isn’t cooling the room 
• An exhaust smell

If you notice any of these signs, call Trio today. We’ll schedule a service call to charge your refrigerant. 

Contact Trio Heating and Air Today

Trio Heating and Air Conditioning is your local California AC service center. We offer air conditioning and central air repair, AC maintenance, and AC installations to Greater San Francisco Bay Area residents. 

If you’re curious about our energy-efficient ACs or want to schedule routine maintenance for your older HVAC system, we’re here to deliver top-tier solutions for all your needs. 

We respond quickly to service requests, use only the best products, and guarantee the highest quality work. Trust us to treat you with respect and take care of your home. Contact us today to schedule an inspection or book a service appointment.