Why is my AC unit freezing up? What owners ask online — answered
Short answer: a frozen AC coil is a symptom, not the disease. Ice forms when the coil gets too cold or too little air passes over it — and in SWFL that almost always means one of three things: a clogged filter, low refrigerant from a leak, or a failing blower motor. Turn the system OFF (fan ON if you can) and let it thaw fully — hours, not minutes — then work through the causes in that order.
The three causes, in the order we check
- Airflow first. Clogged filter, closed supply vents, blocked return — the coil starves for warm air and ices. Cheapest fix on the list.
- Refrigerant charge. Low charge from a leak makes the coil colder than designed, freezing condensate onto it. "Top it up and go" without sealing the leak guarantees a repeat.
- Blower health. A weak blower motor or failed capacitor moves less air even with a clean filter — the coil ices anyway.
What the online threads get right
The forum-standard advice — "turn it off, thaw it, check the filter" — is genuinely correct as first aid. Where we differ from forum wisdom: running a frozen unit to "test it" bends fins and stresses the compressor, and melting ice with a heat gun or sharp tools ruins coils. Thaw passively, then diagnose with numbers.
What our diagnostics show in SWFL
Coastal systems run long seasons; our $129 diagnostic measures pressures, temperature split and amp draw — the three numbers that separate "dirty filter" from "leaking coil" in one visit. Then the written quote, before any work.
FAQ
How long does it take to thaw a frozen AC coil?
Hours with the system off and the fan running — running it frozen risks compressor damage.
Will a frozen coil fix itself?
The ice melts; the cause doesn't. If it iced once, it will ice again until the cause is fixed.