Key Points

• AC units freeze more often than most homeowners expect — especially during the hottest summer months when systems run continuously, which is precisely when San Marcos, TX homeowners are most dependent on them.
• According to the U.S. Department of Energy, proper AC maintenance — including regular filter replacement and coil cleaning — is the most effective prevention against system failures like freezing, which result from the same underlying causes: restricted airflow and refrigerant issues.
• Four things Comfy Air’s free guide covers: how to tell if your AC unit is frozen, how to properly defrost a frozen system, how to identify the root cause so it doesn’t freeze again, and why monitoring the system afterward matters.
• The two most common causes of a frozen AC in Central Texas are clogged air filters restricting airflow and low refrigerant from a leak — both preventable or detectable with routine maintenance.
• A frozen AC should never simply be restarted — the compressor can be severely damaged by running while ice is still present on the coils; proper defrost procedure is essential before restarting the system.
• San Marcos and the Austin metro’s extreme summer heat (95–105°F afternoons) means AC systems run nearly continuously from April through October, which accelerates every condition that leads to freezing — making prevention especially important in this climate.
• Contact Comfy Air for expert AC diagnosis, repair, and maintenance throughout San Marcos, TX and the surrounding Austin metro area.

San Marcos, TX — Comfy Air, one of the fastest-growing HVAC companies in Texas, has released a new guide that explains how to deal with a frozen AC unit. Although it may seem surprising, AC systems freeze more often than expected — especially during the hottest part of the summer when they are working the hardest. Many homeowners are unaware that this can happen or what steps to take when it does.

Why AC Units Freeze in San Marcos, TX

The longer an AC system runs, the more likely it is to freeze up. To support and educate their customers, Comfy Air created an in-depth, easy-to-follow guide addressing this specific issue.

The two most common causes of a frozen AC in the Austin metro: Understanding why freezing happens helps homeowners both prevent it and recognize it early.

Restricted airflow is the most common cause. When airflow through the system is reduced — most often by a clogged air filter, but also by blocked vents, a dirty evaporator coil, or collapsed ductwork — the refrigerant in the evaporator coil can’t absorb enough heat from the indoor air. Without adequate heat transfer, the coil temperature drops below freezing and moisture in the air turns to ice on the coil surface. In San Marcos’s long cooling season, where AC systems run April through October, filters clog faster than in seasonal markets — making monthly filter checks critical. Comfy Air’s AC & furnace air filter replacement service ensures your filter stays clean on schedule.

Low refrigerant from a leak is the second most common cause. When refrigerant levels drop below the system’s designed charge, the pressure in the evaporator coil drops as well — causing the coil temperature to fall below freezing. This is an EPA-regulated repair requiring certified technicians. If your system freezes repeatedly after correct airflow is confirmed, a refrigerant leak is the most likely underlying cause. Comfy Air’s air conditioning repair team handles refrigerant leak diagnosis and repair throughout the San Marcos area.

What Comfy Air’s Frozen AC Guide Covers

The guide, available free of charge here, covers:

• How to tell if an AC unit is frozen — common signs include ice visible on refrigerant lines or the outdoor unit, warm air from vents despite the system running, unusual gurgling or hissing sounds, and water pooling around the indoor unit as ice melts
• How to properly defrost a frozen system — turn the system to “fan only” mode (not off, not cooling) to allow the fan to circulate warm air over the frozen coil without running the compressor; this typically takes 1–3 hours; never chip at ice with tools
• How to identify the root cause so it does not freeze again — check and replace the air filter first; if the filter is clean, the next step is professional refrigerant and coil inspection
• Why monitoring the system afterward is important — a system that refreezes after proper defrost and filter replacement almost certainly has a refrigerant leak or a failing component that requires professional diagnosis before being run again

What to do — and not do — when you discover your AC is frozen:

1. Turn the thermostat to “fan only” — do not turn the system completely off, and do not attempt to run it in cooling mode while frozen
2. Check and replace the air filter immediately — this alone resolves many freezing incidents
3. Allow 1–3 hours for full defrost — check for water around the indoor unit and place towels if needed
4. Once fully defrosted, restart in cooling mode and monitor for 15–20 minutes
5. If the system refreezes or doesn’t cool effectively after restart, turn it off and contact Comfy Air for professional diagnosis — do not continue cycling the system

A Message From Comfy Air

“We take great pride in the service we offer our customers; integrity is non-negotiable, and all too often, we have seen issues with a frozen AC unit,” said Eddie Glidewell. “Many of these issues could be prevented easily, and in cases where they cannot, homeowners need to act quickly. The problem is that most people do not realize an AC can freeze in the middle of the summer. With this guide, we are confident our customers will have enough knowledge to handle the issue themselves or reach out to us for help.”

Preventing frozen AC in San Marcos’s extreme summer climate: Comfy Air’s guidance reflects the specific conditions San Marcos and Austin metro homeowners face. Central Texas summer afternoons routinely reach 95–105°F, and AC systems respond by running for extended continuous periods — sometimes 8–12 hours straight during heat peaks. This continuous operation accelerates the conditions that lead to freezing: filters clog faster, coils accumulate more debris, and refrigerant leak rates become more apparent under sustained load. Annual AC maintenance before the summer season — including coil cleaning, refrigerant level verification, and filter replacement — is the most reliable prevention available. Comfy Air also offers emergency HVAC repair for homeowners whose system freezes during the hottest days when waiting for a scheduled appointment isn’t an option.

Key Takeaways

A frozen AC is a surprisingly common summer problem in San Marcos and the Austin metro — caused most often by restricted airflow from a clogged filter or low refrigerant from a leak. Both causes are detectable and preventable with routine maintenance. The DOE confirms that proper AC maintenance — specifically filter replacement and coil cleaning — is the most effective prevention against system failures. When freezing does occur: switch to fan-only mode (not off, not cooling), replace the filter, allow 1–3 hours for full defrost, then monitor on restart. Do not chip ice, do not run the compressor while frozen, and do not continue cycling a system that refreezes after defrost — that requires professional diagnosis. San Marcos’s extreme summer heat means AC systems run almost continuously from April through October, accelerating every freezing condition and making annual pre-season maintenance critical. Contact Comfy Air for AC repair, maintenance, and emergency HVAC service throughout San Marcos, TX and the Austin metro area.

About Comfy Air — San Marcos’s Leading HVAC Company

Comfy Air is the leading HVAC company in San Marcos, dedicated to providing dependable comfort solutions for residential and commercial customers. Their services include AC replacement, ductwork installation, indoor air quality solutions, and more.