If you’ve noticed your AC freezing up, you’re not alone—especially during those hot Cottonwood summers when your air conditioner is working overtime. It might seem strange for ice to form on your system during 100-degree weather, but it’s actually a fairly common issue. When ice builds up on your AC unit, it can lead to poor cooling, higher energy bills, and even complete system failure if left unchecked.

In this post, we’ll break down the most common reasons behind your AC freezing up, how to fix it, and when it’s time to call in the experts at Trio Cooling, Heating & Plumbing.

Low Refrigerant Levels Can Lead to Your AC Freezing Up

One of the most frequent causes of an AC freezing up is low refrigerant. Refrigerant plays a critical role in absorbing heat from inside your home and releasing it outside. When the refrigerant level is too low, usually due to a leak, the pressure inside the coils drops—causing them to get too cold and freeze over.

Even worse, if the ice spreads, it can damage vital components like your compressor. If you suspect a refrigerant issue, it’s essential to act fast. Although you might be tempted to top it off yourself, refrigerant handling is regulated, and it’s best left to certified technicians like the ones at Trio Cooling, Heating & Plumbing.

Dirty Air Filters Often Cause AC Freezing Up

Sometimes the simplest problems are the easiest to overlook. A clogged or dirty air filter can restrict airflow over your evaporator coils. When there isn’t enough warm air passing over the coils, they get too cold—and yes, this can result in your AC freezing up.

To prevent this, make it a habit to check and replace your air filters every 1 to 3 months, especially during the peak summer season in Cottonwood. Clean filters not only help with freezing issues but also improve indoor air quality and extend the lifespan of your HVAC system.

Blocked or Closed Vents Disrupt Airflow

Another often-missed issue contributing to an AC freezing up is poor airflow caused by blocked or closed vents. If the air in your home can’t circulate freely, cold air can get trapped inside the system, lowering coil temperatures and causing ice buildup.

Walk around your home and make sure all vents are open and unobstructed. Move furniture or rugs if they’re covering vents and check for buildup of dust or debris. Sometimes, resolving airflow issues can be as simple as making sure your HVAC system can “breathe” properly.

Thermostat Problems May Result in AC Freezing Up

Your thermostat plays a bigger role in your AC system than you might think. If it’s malfunctioning, miscalibrated, or installed in the wrong spot—such as near a vent or sunny window—it might cause your system to run too long. And when your system doesn’t cycle off like it should, it can lead to your AC freezing up.

If you’re noticing temperature inconsistencies or that your system doesn’t turn off even after reaching your set temperature, your thermostat could be to blame. Upgrading to a smart thermostat may not only prevent freezing issues but also help save on your energy bill.

Drainage Issues and Humidity Can Freeze Your AC

Arizona may be known for its dry heat, but indoor humidity and drainage problems can still cause an AC freezing up scenario. Your air conditioner removes moisture from the air as it cools. That condensation is supposed to drain away through a condensate line. However, if that line gets blocked, water can back up into the system and cause freezing.

You might notice water pooling around your AC unit or moldy smells near the air handler. If so, it’s time to inspect the drain pan and clean the condensate line—or call Trio Cooling, Heating & Plumbing for a fast and thorough fix.

Frozen Evaporator Coils Are a Warning Sign

Your evaporator coils are where the heat exchange happens. When they get too cold, they freeze. The ice restricts airflow even further, creating a vicious cycle that results in your AC freezing up again and again.

The solution here depends on the root cause—low refrigerant, poor airflow, or drainage problems. If your coils are frozen, first turn off your system and let them thaw completely. Then, address the underlying issue or schedule professional maintenance to prevent a repeat freeze-up.

Oversized AC Units Can Also Freeze Up

Bigger isn’t always better—especially when it comes to air conditioners. An oversized AC unit can cool your home too quickly, which may sound like a good thing, but it doesn’t allow enough time for the system to properly dehumidify the air. This can result in condensation forming and freezing on the coils, leading to—you guessed it—your AC freezing up.

This is why proper sizing is so important. At Trio Cooling, Heating & Plumbing, we perform accurate load calculations before installing a system to ensure it matches your home’s needs perfectly.

What to Do When You See Your AC Freezing Up

If you notice your AC freezing up, take the following steps right away:

1. Turn off your system to prevent further damage.

2. Switch the fan to “On” (not “Auto”) to help melt the ice faster.

3. Check and replace the air filter if it’s dirty.

4. Inspect vents and registers to ensure they’re open and unobstructed.

5. Call a professional if the system keeps freezing or if you suspect refrigerant issues.

Catching and correcting the problem early can save you from more costly repairs or even a total system breakdown.

Preventative Maintenance Stops AC Freezing Up Issues

The best way to avoid your AC freezing up is by scheduling regular preventative maintenance. During a maintenance visit, our technicians will:

• Clean your coils and condensate line

• Check refrigerant levels and pressure

• Inspect electrical components

• Test thermostat calibration

• Replace air filters

• Evaluate airflow and duct integrity

Twice-yearly checkups—ideally in the spring and fall—help keep your system running efficiently and your home comfortable all year long.

Final Thoughts

If your AC is freezing up, don’t ignore it. Whether the problem is dirty filters, low refrigerant, poor airflow, or thermostat trouble, the longer you wait, the worse (and more expensive) it gets. The good news? Most of these issues are fixable—and preventable—with the right care.

At Trio Cooling, Heating & Plumbing, we’re here to help Cottonwood homeowners stay cool and comfortable no matter what the Arizona weather throws your way. Contact us today to schedule an inspection or maintenance visit and put an end to your AC freezing up for good.