Why Is My AC Freezing Up? Causes, Fixes, and When to Call

A frozen air conditioner in July sounds impossible, but it's one of the most common service calls in New Braunfels. When your AC "freezes up," ice forms on the indoor evaporator coil or the copper refrigerant lines — and the system blows warm, weak air while the ice keeps building. Understanding why it happens is the difference between a 90-second filter change and an avoidable compressor failure.

What does it mean when an AC freezes up?

Your evaporator coil is the cold heart of the system: refrigerant expands inside it and absorbs heat from the warm indoor air constantly flowing across it. That airflow is what keeps the coil's surface temperature above freezing. If the airflow drops, or if refrigerant pressure falls too low, the coil dips below 32°F. Central Texas air carries plenty of humidity, so moisture condenses on the cold metal and freezes on contact — and the ice itself then blocks even more airflow. It's a runaway cycle: the more ice forms, the less air moves, and the faster the rest of the coil freezes over. Left running, the ice can encase the coil and the refrigerant lines all the way out to the outdoor unit.

What causes it in Central Texas homes?

• A clogged air filter — the single most common cause. Our cedar season (Ashe juniper, roughly December through February) and spring oak pollen load filters faster than the once-a-season habit most homeowners keep.

• Low refrigerant from a leak — less refrigerant means lower pressure in the coil, which means a colder coil surface. Ice along the larger copper line at the outdoor unit is the classic tell.

• Blocked or closed vents — closing off unused rooms feels thrifty, but it chokes the return airflow the coil was engineered for.

• A failing blower motor or capacitor — the coil can't get the air volume it needs even with a clean filter.

• A dirty evaporator coil — years of fine dust act like a blanket, insulating the coil and trapping cold.

What should you do right now?

Switch the thermostat from COOL to OFF, and set the fan to ON. That moves warm air across the coil and thaws it without pumping more refrigerant through a starved system. While it thaws — a full freeze can take several hours to clear — replace the filter and open every supply and return vent in the house. Put a towel down near the indoor unit; melting ice produces more condensate than the drain pan sometimes handles gracefully. Once the ice is completely gone, try cooling again and pay attention over the next day.

When is it time to stop and call?

If the system re-freezes after a fresh filter and open vents, the likely culprits are a refrigerant leak or a failing blower — neither is a DIY job. Federal law (EPA Section 608) requires certification to handle refrigerant, and "topping off" a leaking system without finding the leak just schedules the next freeze-up. More importantly, running a compressor on a frozen, low-charge system is how a few-hundred-dollar repair becomes a replacement conversation: liquid refrigerant returning to the compressor can destroy it. Our AC repair service in New Braunfels pinpoints the root cause — leak, airflow, or electrical — rather than just thawing the symptom, and every diagnosis comes with an upfront written price before any work begins.

How do you keep it from happening again?

Freeze-ups are largely preventable, which is why they're a maintenance story more than a repair story. Coil cleaning, refrigerant level checks, and airflow verification are standard items in a professional tune-up. The Team HomeFront Club builds that rhythm in: bi-annual visits (a pre-summer cooling inspection plus pre-winter heating maintenance) from $15.75/month or $189/year, with VIP priority service, no service fees, and 15% off any repairs the inspection uncovers. Between visits, the homeowner's side of the job is simple — see the pre-summer checklist you can do yourself, and our guide to how often you should service your AC in Texas for the full seasonal picture.

What if this keeps happening on an old system?

Repeated freeze-ups on a unit past its tenth Texas summer often signal a coil or leak problem that isn't economical to keep chasing. Before you pay for the next fix, run the numbers in the $5000 rule for repair vs. replacement — five minutes of arithmetic that tells you whether the next dollar belongs in this system or its successor. Straight answers, zero pressure; that's how Team HomeFront operates.