Why is my AC freezing up?
Short answer: ice on your AC lines or coil almost always means one of two things — restricted airflow (usually a dirty filter) or low refrigerant from a leak. Turn the cooling off, let it thaw, and check the filter. If the ice comes back, it needs a technician.
Three steps, before anything else.
A frozen system running dry can take out the compressor — the most expensive part in the whole machine. Stop the damage first, diagnose second.
Set the thermostat from COOL to OFF. Leaving it running while iced over strains the compressor and makes the ice worse.
Switch the fan setting from AUTO to ON. Moving indoor air over the coil melts the ice from the inside — usually 1–3 hours, longer if it's badly iced. Never chip or pry at the ice.
While it thaws, pull the return filter. If you can't see light through it, that's likely your culprit — replace it before turning cooling back on.
Six reasons an AC ices over.
The most common cause by far. A clogged filter chokes airflow over the evaporator coil, the coil temperature drops below freezing, and humidity in the air freezes onto it.
Refrigerant doesn't get "used up" — if it's low, there's a leak. Low charge drops coil pressure and temperature, which builds ice. This one always needs a technician: finding and fixing the leak, then recharging.
Closing vents in unused rooms feels thrifty, but it starves the system of airflow the same way a dirty filter does. Keep supply and return vents open and unblocked by furniture.
Years of dust on the indoor coil acts like a blanket — the coil can't absorb heat, runs cold, and ices. This is one of the things a twice-yearly tune-up prevents.
If the blower is weak or failing, not enough air moves across the coil even with a clean filter. Often shows up alongside weak airflow at the vents or a humming sound at the air handler.
Running the AC when it's below about 60°F outside — cool North Texas spring nights — can ice a system that's perfectly healthy. Use the fan or open windows instead on those nights.
Thawed it and it froze again? That's our cue.
If the ice returns after a thaw and a fresh filter, you're likely looking at a refrigerant leak, a coil that needs cleaning, or a blower problem — none of which are DIY territory. Same goes for hissing or bubbling sounds at the lines, or air that stays warm after the thaw. We diagnose it, quote the fix in writing, and it's the same crew whether you're in Sherman, McKinney, or Frisco. See our full AC repair service.
The questions that come with the ice.
How long does a frozen AC take to thaw?
With cooling off and the fan set to ON, usually 1–3 hours. A badly iced coil can take up to 24. Don't rush it with tools or hot water — coil fins bend easily and refrigerant lines can be punctured.
Can I keep running the AC while it's frozen?
No — this is the one that turns a $100 problem into a compressor replacement. An iced coil can send liquid refrigerant back to the compressor, which it isn't built to handle. Shut cooling off as soon as you see ice.
I replaced the filter and it froze again. Now what?
Then the airflow-side easy fix is ruled out, and it's most likely a refrigerant leak, dirty coil, or blower issue. That's a diagnostic call — (903) 891-9154, answered 24/7. Most Sherman-area calls are same-day.
How do I keep it from freezing again?
Change the filter every 1–3 months (monthly in peak Texas summer), keep vents open, and have the coil cleaned and charge checked at a spring tune-up. That's exactly what our maintenance plan covers, twice a year.