Thaw first — carefully
Switch COOL off and set the fan to ON. Warm indoor air melts the ice over 2–4 hours (a thick block can take longer). Put towels around the indoor unit and check the drain pan — melting ice produces more water than the pan sometimes handles. Never chip ice off the coil; the fins bend and the tubing punctures easily.
Cause #1: starved airflow (the cheap one)
The coil needs a steady stream of warm air to stay above freezing. A clogged filter, closed or blocked vents, or a dirty coil starve it. After thawing: replace the filter, open every vent, and run COOL again. If it stays ice-free for 24+ hours, you found the cause for the price of a filter.
Cause #2: low refrigerant (the pro one)
Low refrigerant drops the coil's pressure and temperature until moisture freezes on contact. Refrigerant doesn't get 'used up' — if it's low, it leaked, and the leak needs finding. Topping off without fixing the leak is renting cold air by the season. Refrigerant work legally requires an EPA-certified technician.
Prevent the next freeze
- Change filters on schedule (see the filter guide).
- Keep at least 80% of vents open — closing rooms chokes airflow more than it saves.
- Have the evaporator coil cleaned when visibly dusty.
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