Why Is My AC Frozen in the Middle of a Texas Summer?

It's one of the strangest things a homeowner can see: it's 103° in Waco, your AC is running nonstop, and the copper line going into your house is wrapped in ice. Here's what's actually happening and what to do about it.

Why Is My AC Frozen in the Middle of a Texas Summer?

Why an air conditioner freezes in 100° heat

Your evaporator coil gets cold by design — refrigerant inside it absorbs heat from your indoor air. But it needs a steady flow of warm air across it to stay above freezing. Starve that airflow, or drop the refrigerant pressure, and the coil plunges below 32°. Humidity in the air — and Waco has plenty — freezes onto the coil like frost on a freezer wall, and the ice builds until airflow stops entirely.

The three causes we see in Waco homes

  • A filthy filter. The #1 cause, and Central Texas makes it worse: cedar pollen from January through April, then oak, then grass seed and dust all summer. A clogged filter suffocates the coil. During peak season in McLennan County, check your filter monthly.
  • Low refrigerant. A slow leak drops system pressure, which drops coil temperature. The ice is a symptom — topping off refrigerant without finding the leak just rents you a few weeks.
  • Blower problems. A dying blower motor, caked blower wheel, or closed/blocked supply vents restrict airflow the same way a dirty filter does.

What to do right now

Turn the system off at the thermostat — or set it to fan-only — and let the ice melt completely. This takes hours, not minutes, and yes, the house will get warm. Running it frozen can slug the compressor with liquid refrigerant and turn a $15 filter problem into a $2,000 compressor problem. Never chip at the ice; you'll puncture the coil. Once it's thawed, replace the filter and restart. If it freezes again, you have a refrigerant or airflow problem that needs a technician.

Preventing a repeat

Monthly filter checks May through September, keep supply vents open (closing them doesn't save money — it freezes coils), keep the outdoor unit clear of cottonwood and grass clippings, and get a spring tune-up so refrigerant levels are verified before the heat arrives. Frozen coil keeping coming back? Call (254) 555-0170 and we'll connect you with a Waco tech who'll find the actual cause.