It's 100 degrees outside and there's ice on your air conditioner. It feels backwards, but a frozen AC is one of the most common summer breakdowns we see in San Antonio. Here's why it happens, the one thing to do right now, and how to keep it from coming back.
Do this first: turn it off
If you see ice on the copper lines, the indoor coil, or the outdoor unit, shut the system off at the thermostat. Then set the fan to ON (this blows warm room air over the coil and speeds up thawing). Running a frozen AC forces liquid refrigerant back into the compressor, and that can destroy the single most expensive part in your system. A two-dollar problem turns into a two-thousand-dollar one fast. Turn it off and let it thaw completely, which usually takes two to four hours.
While it thaws, let's figure out why it froze.
1. Restricted airflow (the usual suspect)
Your AC needs a steady flow of warm air over the coil to work. Choke that airflow and the coil gets too cold and freezes. The top causes:
- A dirty air filter. The number-one cause. Pull it. If you can't see light through it, replace it.
- Closed or blocked vents. Furniture over a return, too many supply vents closed off. Open them up.
- A dirty blower or coil. Dust builds up over years of San Antonio summers and insulates the coil. This one needs a tech to clean properly.
2. Low refrigerant
Low refrigerant drops the pressure in the coil, which drops the temperature below freezing. And low refrigerant always means a leak, because it's a sealed system that doesn't burn off over time. This is a licensed-tech repair: the leak has to be found, sealed, and the system recharged. If your filter is clean and it still freezes, this is the likely cause.
3. Running it too cold at night
San Antonio days are brutal, but nights cool off. Running your AC hard when it's below about 62 degrees outside can cause the coil to freeze. If you like it cold at night, that's fine, but if you're seeing morning ice, try nudging the thermostat up a couple degrees overnight.
4. A failing blower fan
If the indoor fan motor is weak or failing, it can't push enough air across the coil, and you get the same freeze-up as a dirty filter. This one needs a tech to diagnose and replace.
How to stop it from happening again
- Change your filter every 1 to 2 months during cooling season. In San Antonio's dust and run-time, monthly is smart.
- Keep vents open and furniture clear of returns.
- Get a yearly tune-up. A pro cleans the coil, checks refrigerant, and catches a weak blower before it freezes you out in August.
When to call us
If you've thawed it, changed the filter, opened your vents, and it freezes up again, the problem is inside the sealed system (refrigerant or coil) or in the blower. Those aren't homeowner fixes, and the longer a system runs frozen, the more it costs.
Call (210) 552-5850. We'll get you running.
Matador Cooling and Heating is veteran-owned, licensed (TACLB134154E), and we offer same-day and 24/7 emergency service across San Antonio. We find the actual cause of the freeze-up, not just chip the ice off and leave.
Schedule AC repair or call (210) 552-5850. AC down in the middle of the night? That's what our 24/7 emergency service is for.
Need it fixed today?
Veteran-owned, licensed, and available 24/7 across San Antonio. We find the real problem and tell you what it costs before we start.
Call (210) 552-5850