It sounds like a contradiction: the hottest afternoon of the year, and your refrigerant line looks like a frozen daiquiri straw. Yet frozen coils are one of our most common summer calls across Lafayette Parish — and they always trace back to one of two root causes.
Cause One: Airflow Starvation
Your evaporator coil gets cold by absorbing heat from indoor air blowing across it. Starve that airflow and the coil temperature plunges below freezing; the humidity it normally condenses starts freezing instead. The usual suspects:
- A clogged filter — the number-one cause, especially during live-oak pollen season
- Closed or blocked supply vents — that “unused room” strategy backfires
- A struggling blower motor or caked blower wheel
- Crushed or disconnected ductwork in a hot attic
Cause Two: Low Refrigerant
Refrigerant doesn’t get “used up” — if the charge is low, there’s a leak. Low charge drops coil pressure and temperature, and ice follows. Topping off without finding the leak is money thrown into the Acadiana sky; proper repair means leak detection, a fix, and a verified recharge.
What to Do the Moment You See Ice
- Turn cooling OFF at the thermostat immediately. Running a frozen system can slug liquid refrigerant back into the compressor and destroy it — turning a modest repair into a replacement conversation.
- Switch the fan to ON. Room-temperature air across the coil thaws it safely. Expect water as it melts — this is when weak condensate drains reveal themselves, so keep an eye out.
- Check the filter. If it’s grey and matted, replacing it may solve the whole problem. If it’s clean, the issue is deeper and needs a tech.
- Give it hours, not minutes. A fully iced coil can take most of a day to thaw. Don’t restart early.
Keeping It From Coming Back
Monthly filter checks during peak season, twice-yearly maintenance with coil cleaning and charge verification, and fixing small airflow complaints before they become frozen ones. In Lafayette’s humidity, a system that ices once will ice again — until the root cause is actually fixed.
The bottom line
Ice on your AC is a symptom, not the disease. Turn it off, thaw it, check the filter — and if it refreezes, get the airflow or the leak diagnosed before the compressor pays the price.