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Why Is My AC Freezing Up? Causes of a Frozen Evaporator Coil
June 10, 2026
Ice on your AC? Learn what causes a frozen evaporator coil, how to thaw it safely, and when to call for repair.
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Seeing ice on your air conditioner’s indoor coil or refrigerant line is never normal — and running a frozen system can damage the compressor, one of the most expensive parts to replace. Here is what causes an AC to freeze up and what to do about it.
Common causes of a frozen AC coil
- Restricted airflow: a dirty filter, closed vents, or a blocked return is the number-one cause. Without enough warm air across the coil, it drops below freezing.
- Low refrigerant: a leak lowers system pressure and freezes the coil. This needs a professional to find and seal.
- Dirty evaporator coil: built-up grime insulates the coil and encourages icing.
- A failing blower motor: if the fan isn’t moving enough air, the coil freezes.
What to do right now
- Turn the system to OFF (run the fan only) to let the ice thaw — this can take a few hours.
- Replace the air filter and open all supply and return vents.
- Once fully thawed, restart in COOL and watch for ice returning.
If it freezes a second time, you likely have a refrigerant or mechanical issue that needs a technician — don’t keep running it.
Fast AC repair in the south suburbs
Always Ready Repair fixes frozen coils, refrigerant leaks and airflow problems with honest, transparent pricing. We provide AC repair in Tinley Park, Orland Park and across Chicagoland. Book service or call (708) 671-0813.
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