Why Your AC Is Freezing Up and How to Fix It
Finding ice on your AC in the middle of summer seems paradoxical, but it's a common problem with specific causes. Here's what to know.
Ice forming on your air conditioner is never a good sign. While it might seem like the system is just working really hard, frozen components actually prevent cooling and can damage the compressor.
Why ACs Freeze
Air conditioners work by absorbing heat from indoor air. When something disrupts this process, the refrigerant in the evaporator coil gets too cold and moisture from the air freezes on contact.
The Main Causes
Restricted Airflow This is the most common cause. When air can't flow across the evaporator coil properly, the coil gets too cold.
Causes include: - Dirty air filter (the #1 culprit) - Closed or blocked supply vents - Dirty evaporator coil - Failing blower motor
Low Refrigerant When refrigerant levels drop due to a leak, pressure in the system decreases, causing temperatures to drop below freezing.
Running in Cold Weather If you run your AC when outdoor temperatures are below 60°F, the system can freeze. The refrigerant cycle isn't designed for low ambient temperatures.
Mechanical Failures Failing components like the blower motor, fan, or refrigerant metering device can cause freeze-ups.
What to Do When It Happens
1. Turn off the AC (but leave the fan on if possible) 2. Let the ice melt completely—this can take several hours 3. Check and replace the air filter if dirty 4. Once melted, try running the system again 5. If it freezes again, call for service
Don't Do This
Never try to chip or scrape ice off the coils. You can easily damage the delicate fins and create refrigerant leaks.
Prevention
The best prevention is regular maintenance—clean filters, annual tune-ups, and addressing small problems before they become big ones.