AC Troubleshooting
Frozen Evaporator Coil: Causes & What to Do
Updated January 2026 • 5 min read
First Step: Turn your AC to "OFF" at the thermostat but leave the fan on "ON." This allows air to circulate and melt the ice. Do NOT try to chip ice off—you can damage the coils.
How to Tell if Your Coil is Frozen
- Ice visible on refrigerant lines (copper pipes going to indoor unit)
- Ice buildup on the indoor unit itself
- Water dripping or pooling around indoor unit
- AC running but warm air from vents
- Hissing or bubbling sounds from indoor unit
Why Evaporator Coils Freeze
1. Restricted Airflow (Most Common)
When airflow over the coil is reduced, the coil gets too cold and moisture freezes on it. Common causes:
- Dirty air filter - The #1 cause of frozen coils
- Blocked return vents - Furniture or rugs covering vents
- Dirty evaporator coil - Dust buildup on coil surface
- Blower motor problems - Fan not moving enough air
2. Low Refrigerant
When refrigerant is low (from a leak), the remaining refrigerant expands more than it should, causing the coil to get extremely cold. This requires professional diagnosis and leak repair.
3. Running AC When It's Too Cold Outside
AC systems aren't designed to run when outdoor temps are below 60°F. The coil can freeze in these conditions.
What to Do Right Now
- Turn AC off, fan on: Let the ice melt (may take several hours)
- Check and replace your filter: If it's dirty, this may be your problem
- Check vents: Make sure all return vents are open and unobstructed
- Wait until fully thawed: Don't restart AC until all ice is gone
- Call for service if: It freezes again after thawing, or if your filter was clean
Warning:
Don't run your AC while the coil is frozen. This can damage the compressor—the most expensive component in your system.
Coil Keeps Freezing?
If a clean filter doesn't solve it, you likely have a refrigerant leak or blower issue. We diagnose properly.
📞 Call 832-403-7466