Why Your AC Freezes Up in a Lima Summer (And What to Do)

The first time it happens, nobody believes it: your compressor never shuts off, rooms keep heating up, and thick ice coats the copper outside. Freezing weather in the middle of a West Central Ohio heatwave sounds impossible until you know how refrigerant cycles work — and that knowledge protects your compressor from serious damage.

How a Coil Freezes in 100-Degree Heat

That evaporator coil is supposed to sit at 35 to 40 degrees, skirting just above freezing by intention. Your blower's airflow is what holds it there. Cut that airflow or lose refrigerant, and the coil plunges past the freezing point. Moisture on the fins becomes frost, the frost seals in cold, and you are trapped in a loop that leaves the coil a solid iceberg while your vents blow nothing but warm air.

The Two Causes We Find in Lima

Restricted airflow (about 70% of cases). A filter choked with glacial plain pollen, a clogged evaporator coil face, closed or crushed duct runs, or a dying blower motor. In our dusty region, the filter is the first suspect every single time — especially after storm season.

Low refrigerant (about 30%). Refrigerant doesn't get used up — if it's low, there's a leak, usually at a service valve, a rubbing line, or an aging coil. Topping off without finding the leak is money thrown away; the ice will be back in weeks.

What to Do Right Now

Turn the cooling off. Set the thermostat to off and the fan to on — moving air speeds the thaw. A fully iced coil takes 4 to 24 hours to melt completely, and it will dump a lot of water. Put towels around the air handler and watch the drain pan; this is also when clogged drain lines reveal themselves.

Change the filter while it thaws, and make sure no supply or return vents are blocked by furniture or rugs.

Do not chip the ice and do not restart the system while ice remains. Restarting frozen can slug the compressor with liquid refrigerant — the single most expensive mistake a homeowner can make, turning a $200 fix into a multi-thousand-dollar replacement.

After a complete thaw and a clean filter, another freeze means the issue runs deeper than airflow. Give us a call. We will locate the leak or pinpoint the restriction and repair the real source, not just the symptom.