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Window air conditioner · Repair Copilot

Window AC freezing up

A window AC freezing up — ice on the front coils, weak airflow, then water everywhere when it melts — is almost always restricted airflow from a dirty filter or coils, or running it when it's too cold out. It's usually a quick DIY fix. Show SightLine the unit and a friendly handyman persona walks you through thawing it and clearing what choked the airflow.

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Steps to fix window ac freezing up

  1. Turn the cooling OFF but leave the FAN running (or set to fan-only) to melt the ice — never chip or scrape it off.
  2. Once fully thawed and dry, unplug the unit before you clean anything.
  3. Pull and wash the air filter — a clogged filter is the #1 cause of a frozen coil because it starves airflow; let it dry fully before reinserting.
  4. Check the coils: gently vacuum or brush dust off the front (evaporator) fins, and clear leaves/dirt from the rear condenser fins.
  5. Don't run a window unit when it's cold outside (below about 60°F) — low outdoor temps make the coil ice up; and make sure the vents aren't blocked by curtains or furniture.
  6. If the filter and coils are clean and it still ices over on a warm day, the refrigerant is likely low (a sealed-system leak) — that's a repair or replacement, not DIY.

Safety first: if a step calls for gas, a main water or sewer line, a service panel or main breaker, or a sealed refrigerant system, stop and call a licensed pro — Repair Copilot will tell you when you're there.