What Is Causing Ice To Form on Your AC Unit in Lewisville, TX?

Key Points

• Ice on your AC unit is a warning sign — not a good one
• The most common causes are a dirty air filter and low refrigerant levels
• Running a frozen AC unit can damage components and drive up energy bills
• You can melt ice using fan-only mode, but the root cause must still be fixed
• A licensed Lewisville HVAC technician can diagnose and repair the issue fast

Discovering ice on your home’s air conditioning unit might seem harmless — or even reassuring, as if your system is working overtime to cool your home. But a frozen AC unit is actually a serious warning sign, not a good one. In the middle of a Texas summer, a freezing AC means reduced cooling, higher energy bills, and potential damage to your system if left unaddressed. If you notice ice forming on your unit, it’s time to schedule AC services in Lewisville, TX as soon as possible.

But what exactly causes ice to form on an AC unit, and why is it so damaging? More importantly, what can you do to fix it and keep it from happening again? At BCI Mechanical, we help Lewisville homeowners tackle this issue every summer. Here’s everything you need to know.

Top Reasons Your AC Unit Is Freezing Up in Lewisville

Ice most commonly forms on the evaporator coils — the components inside your home responsible for absorbing heat from your indoor air and moving it outside. When something disrupts this heat exchange process, the coils drop below freezing and ice begins to build up. Understanding what causes this disruption is the first step toward fixing it.

While there are several possible causes, the two most common culprits in Lewisville homes are restricted airflow and low refrigerant levels. Both prevent the evaporator coils from functioning properly and can lead to a fully frozen air conditioner if not addressed quickly.

Poor Airflow From a Dirty Air Filter

One of the simplest and most overlooked causes of a frozen AC unit is a clogged air filter. When your filter is dirty, warm air can’t flow freely over the evaporator coils. Without that warm airflow, the coils get too cold and begin to freeze. According to ENERGY STAR guidelines, replacing your filter every one to three months is one of the most effective ways to maintain your system’s efficiency and prevent issues like evaporator coil freezing.

Regularly changing your air filter is one of the easiest things you can do to protect your AC system. If you’re unsure how often to replace it or what type your system requires, our team can walk you through it during a routine AC maintenance visit in Lewisville.

Low Refrigerant Levels or a Faulty Expansion Valve

Low refrigerant is another leading cause of a frozen AC unit. When refrigerant levels drop — typically due to a leak in your system — the pressure inside your evaporator coils falls too low, causing them to get excessively cold and freeze over. A faulty expansion valve that restricts refrigerant flow can produce the same result. Either way, the system struggles to maintain proper temperature regulation.

It’s important to note that refrigerant recharging is not a DIY task. Under EPA Section 608 regulations, only certified HVAC technicians are permitted to handle refrigerants legally. Attempting to recharge refrigerant yourself can result in fines, further system damage, and safety hazards. A licensed technician will find the leak, make the repair, and recharge your system correctly.

Other Causes of a Frozen AC Unit Worth Checking

If a dirty filter and low refrigerant aren’t the culprits, a few less common factors could be causing your AC to freeze up. A malfunctioning blower motor reduces airflow over the coils much like a clogged filter does, while dirty evaporator coils can insulate the coils and prevent heat absorption entirely. Running your AC on an unusually cool night can also cause freezing, since systems aren’t designed to operate efficiently in low outdoor temperatures.

These issues are harder to self-diagnose and typically require a professional inspection. If basic troubleshooting hasn’t resolved your frozen AC problem, it’s best to call a certified HVAC technician in Lewisville who can pinpoint the exact cause and recommend the right fix.

What Happens If You Keep Running a Frozen AC Unit?

Continuing to run your AC while it’s frozen puts serious stress on the entire system. The unit has to work much harder to push air through ice-blocked coils, which strains the compressor and other components. The U.S. Department of Energy notes that a poorly maintained AC system can use significantly more energy than a well-maintained one — and a frozen unit is one of the fastest ways to send your electricity bills soaring.

Beyond energy costs, a frozen AC unit often fails to cool your home effectively, leaving you uncomfortable even as the system runs continuously. And once the ice melts, the resulting water can leak into surrounding components, causing moisture damage to your system and nearby areas of your home. The longer you wait, the more expensive the repair tends to become.

How to Remove Ice From Your AC Unit the Right Way

If you notice ice on your AC unit, the first step is to turn the system off and switch it to fan-only mode. This circulates air over the coils without continuing the cooling cycle, which helps the ice melt safely within a few hours. Avoid using a heat gun, hair dryer, or sharp tools to chip the ice away — these can damage delicate coil fins and refrigerant lines, turning a fixable problem into a costly one.

Melting the ice is just step one. Once your system is thawed, you must address whatever caused the freezing in the first place, or it will happen again. Replace a dirty air filter, check for visible refrigerant leaks, and inspect your vents for blockages. If the problem persists or you’re not sure what caused it, don’t hesitate to reach out for professional AC repair in Lewisville, TX to get to the root of the issue.