It sounds backwards: your air conditioner is covered in ice in the middle of a Florida summer. But a frozen AC coil is one of the most common problems we see on the Treasure Coast, and it almost always points to one of a few specific issues. Here is what is happening and what to do.
First: turn the AC off
If you see ice on the indoor coil or the copper refrigerant line, switch the system to OFF (or fan-only) and let it thaw. Running a frozen system can damage the compressor, the most expensive part of your AC. Give it a few hours to melt before troubleshooting.
Why AC coils freeze up
1. Restricted airflow (the most common cause)
Your AC needs a steady flow of warm air over the coil to keep it from getting too cold. When airflow is blocked, the coil drops below freezing and condensation turns to ice. Usual suspects:
- A dirty air filter, check and replace it first.
- Closed or blocked vents, keep supply and return vents open and unobstructed.
- A dirty blower or evaporator coil, which needs professional cleaning.
2. Low refrigerant
Low refrigerant, often from a leak, drops the pressure in the system and causes the coil to freeze. A technician needs to find the leak, repair it, and recharge the system.
3. Running the AC when it is cool out
Running the AC on a cooler night (below about 62°F) can cause freezing. It is rare in Florida, but worth knowing.
4. Drainage or fan problems
A failing blower fan or a clogged condensate drain can also lead to a frozen coil.
How to prevent it
- Change your filter regularly, monthly during peak cooling season.
- Keep vents open and furniture clear of them.
- Get an annual tune-up so a tech can clean the coil, check refrigerant, and catch problems early.
Still freezing up? Call us.
If your coil keeps freezing after you have replaced the filter and let it thaw, you likely have low refrigerant or a dirty internal coil. Do not keep running it; you risk a costly compressor failure. Subzero Cooling & Heating has served Port St Lucie and the Treasure Coast for 31 years. Call (772) 344-3700 for fast diagnosis and repair.