What Causes A Commercial Air Conditioner Unit To Freeze Up
When managing a commercial property—whether it's a hotel, senior living facility, or multi-unit building—keeping your air conditioning units running efficiently is critical. One common yet frustrating issue is when a commercial AC unit freezes up. This problem not only disrupts comfort but also signals underlying mechanical or airflow issues that can lead to costly repairs if left unaddressed. At AACS, we’ve seen how frozen commercial AC units can impact business operations, especially in the hot and humid climate of South Florida.
Understanding why this happens is the first step in preventing breakdowns and ensuring your HVAC system keeps running when you need it most. Freezing can happen for a variety of reasons, even during the summer months. Most issues relate to poor airflow, low refrigerant, or faulty components—problems that often go unnoticed until the unit stops working altogether. In a commercial setting, where dozens or even hundreds of people rely on consistent cooling, this kind of failure is simply unacceptable.
In this guide, we break down the most common reasons commercial air conditioners freeze up, how to fix them, and when to call in a professional like Advantage Air Conditioning Solutions, Inc. Let’s dive in.
Reasons for an AC unit freezing in Summer
It might seem counterintuitive, but air conditioners—especially commercial units—can freeze even during the peak of summer. This is a common issue in South Florida, where AC systems are under constant pressure to deliver round-the-clock cooling in high-temperature, high-humidity environments. For businesses operating hotels, motels, or senior living facilities, a frozen AC unit can disrupt daily operations, affect guest comfort, and lead to costly downtime.
Freezing typically points to underlying mechanical or airflow problems that prevent the system from operating efficiently. While it’s easy to blame the heat, the true culprits often include poor maintenance, airflow restrictions, or low refrigerant levels. Left unchecked, a frozen unit can escalate into a full system breakdown—something no commercial property can afford.
Below, we break down the most common reasons your commercial AC might freeze up during the summer and what to watch out for before the issue becomes a major repair.
Low Refrigerant Levels
Low refrigerant is one of the leading causes of AC freeze-ups in commercial units. Refrigerant is essential for the heat exchange process—it absorbs heat from inside the space and releases it outside. When refrigerant levels drop due to a leak or improper charge, pressure in the system falls. This can cause the evaporator coil to become too cold, eventually leading to ice formation on the coil.
For commercial PTAC and VTAC systems, this issue is even more problematic. Since these units are often installed wall-by-wall and serve individual rooms, one leak can disrupt the comfort of multiple guests or residents. If you notice ice buildup along the refrigerant lines or reduced airflow, call a professional technician immediately. At AACS, we offer quick diagnostics and professional recharge services to restore your system safely and efficiently.
Preventative maintenance is key here. A regular service schedule will allow technicians to detect refrigerant leaks early before they escalate. Not only will this prevent freeze-ups, but it will also improve energy efficiency and prolong the life of your commercial units.
Dirty Air Filters or Blocked Vents
Dirty air filters and blocked return vents are another frequent cause of frozen commercial AC systems. In commercial environments where AC units run continuously, filters can get clogged quickly with dust, debris, and airborne particles. When airflow is restricted, the evaporator coil doesn’t receive enough warm air to function correctly—this causes the coil to get too cold and eventually freeze over.
Blocked vents also restrict proper airflow across the system. In hotels and senior facilities, vents may be accidentally covered by furniture, curtains, or other objects. Without sufficient airflow, your commercial AC is unable to regulate temperature effectively, leading to freezing and shutdowns.
To prevent this, establish a routine filter replacement policy—at least once a month during peak season. Encourage staff to check vents during room turnovers or cleaning cycles. At AACS, we can train your maintenance team to spot airflow issues early and perform routine tasks that prevent system downtime.
Damaged or Faulty Wiring
Electrical issues are a less obvious but critical cause of AC freeze-ups, especially in older buildings or systems with outdated wiring. Faulty wiring can prevent components like the blower fan or compressor from functioning properly. If the blower motor doesn’t run at full speed, airflow drops—and as we’ve mentioned, poor airflow can lead directly to freezing.
Commercial PTAC and VTAC units rely on stable electrical signals for continuous operation. Faulty thermostats, damaged wiring, or failing capacitors can send mixed signals to the system, causing it to cycle incorrectly or run at half capacity. Over time, this increases wear and leads to ice buildup.
Only licensed HVAC technicians should handle electrical diagnostics. At AACS, we inspect your commercial units for wiring issues as part of our full-service maintenance program. We also provide emergency repair services if your system fails unexpectedly due to electrical faults.
Clogged Condensate Drain Line
Commercial air conditioners extract a significant amount of moisture from the air, especially in Florida’s humid climate. This moisture is drained away through a condensate line. If that drain becomes clogged with algae, dirt, or mineral deposits, water can back up and freeze on the coil.
Clogged drain lines are common in wall-mounted commercial systems because they often go unchecked for long periods. In facilities with dozens of units, it's easy to overlook one until a leak, water damage, or system freeze-up occurs. Not only does this lead to ice on the coil, but it can also result in water damage to floors and walls—creating safety and liability risks.
To prevent this, schedule regular cleanings of condensate lines. At AACS, we use specialized tools to clear clogs safely and offer preventive treatments that reduce future build-up. A clear drain line means better performance and fewer surprises.
How to fix an AC unit that freezes up?
Fixing a frozen commercial AC unit starts with turning off the system completely to allow the ice to melt. Do not try to chip away at the ice manually, as this can damage sensitive coils or fins. Next, check air filters and vents for any blockages. Replace dirty filters immediately and ensure nothing is obstructing airflow.
Once the unit has thawed, turn it back on and monitor its performance. If freezing reoccurs, it’s likely due to an underlying mechanical or refrigerant issue that requires professional attention. AACS technicians perform full diagnostics—including checking refrigerant pressure, inspecting wiring, and cleaning the evaporator coils.
Avoid DIY repairs for commercial units. These systems are more complex than residential ones and serve many people. Our team at AACS is equipped to handle commercial AC repairs quickly, minimizing downtime and restoring comfort efficiently.
Can a dirty air filter cause AC to freeze?
Yes, a dirty air filter can absolutely cause a commercial AC unit to freeze up. When filters are clogged, airflow becomes restricted. Without enough warm air passing over the evaporator coil, the coil temperature drops below freezing, resulting in ice buildup.
In a commercial setting, where systems are expected to run continuously and reliably, dirty filters can quickly lead to systemic failures. This can mean uncomfortable guests, loss of business, and expensive repairs.
Replacing filters regularly is one of the simplest yet most effective ways to prevent AC freeze-ups. AACS can help you set up a custom filter maintenance plan tailored to your building’s usage and system type.
Is it bad for an AC to freeze up?
Yes—freezing is a red flag that your commercial AC unit is not working as intended. Ice buildup can damage internal components, reduce efficiency, and eventually lead to system failure. For businesses, this means increased energy bills, customer complaints, and unplanned repair costs.
Freezing also signals that your system may be running under strain, whether due to electrical issues, refrigerant loss, or poor maintenance. Ignoring it can shorten the lifespan of your unit significantly.
AACS takes freeze-ups seriously. When you contact us, we inspect the entire system to find the root cause and ensure your unit returns to peak performance. Don’t let a frozen coil turn into a major business disruption—act early.
Will a bad blower motor cause AC to freeze up?
Absolutely. The blower motor is responsible for circulating air over the evaporator coil. If it’s malfunctioning or running at low speed, airflow drops—and we know low airflow is a major cause of freezing.
Commercial blower motors take on a heavy workload, especially in high-occupancy buildings. Over time, wear and tear can reduce their efficiency or cause them to fail completely. If you notice unusual noises, uneven cooling, or poor air circulation, your blower motor might be on its way out.
At AACS, we offer full diagnostics and motor replacement services. Our team ensures your commercial units are running smoothly, keeping your facility cool and your operations running without a hitch.
A frozen commercial air conditioner is more than just an inconvenience—it’s a warning sign that your system isn’t operating properly. From low refrigerant and poor airflow to electrical faults and clogged drain lines, several preventable issues can cause a unit to ice over, even during the hottest months. For commercial properties in South Florida, staying ahead of these problems is crucial to maintaining comfort, safety, and efficiency.
At Advantage Air Conditioning Solutions, Inc., we specialize in diagnosing and repairing commercial AC units quickly and professionally. Our experienced team understands the unique challenges of PTAC and VTAC systems used in hotels, motels, and senior living facilities. If your unit is freezing up or showing signs of trouble, don’t wait—contact AACS today to keep your system running strong all season long.
