Your AC doesn't have to quit completely to need attention. In a Columbia summer, catching a problem early can save you from a breakdown on the hottest day of the year. Here are the warning signs our technicians see most — and how urgent each one is.

Try these safe checks first

Make sure the thermostat is set to cool, replace its batteries if they're low, check the filter and make sure vents and return grilles aren't blocked. Outside, clear leaves and plants from around the unit without opening it. Still not cooling? Time to call. Don't open panels, keep resetting a breaker or bypass a float switch.

Call right away

  • Smoke, sparks or a burning smell: get everyone out and call 911 first.

  • Water near electrical equipment: stay out of the area and don't touch the unit or switches.

  • Ice on the lines or indoor coil: turn cooling off. Don't chip it or melt it with heat. Ice usually means an airflow or refrigerant problem.

  • No cooling in dangerous heat: move older adults, infants and pets somewhere cool, and tell us when you call.

Schedule a repair soon

Warm air or weak airflow

Could be a clogged filter, a blocked return, a duct problem, a blower issue, an electrical part or refrigerant. Note whether every room is affected and when it started.

Turning on and off constantly

Short-cycling wears out equipment and leaves the house clammy. Causes range from thermostat and airflow problems to an oversized system or an electrical fault.

New noises

Clicking, buzzing, grinding or banging can point to several different parts. Don't try to track it down yourself — note when it happens and where it seems to come from.

Water around the indoor unit

Often a clogged condensate drain — very common in our humid summers. Don't pour chemicals down the drain or bypass the float switch.

Worth a check-up

  • Some rooms much warmer than others: often ductwork, insulation or airflow — not the AC itself.

  • Musty smell: can point to moisture in the system or drain.

  • Higher bills: compare your usage (kWh) with the same month last year. A jump without a change in weather or habits can mean the system is working harder than it should.

  • Frequent repairs: a good reason for a full diagnosis. See our repair vs. replacement guide.

Symptoms help your technician know where to start, but they don't identify the failed part on their own. A proper diagnosis does.

AC acting up? On Call's NATE-certified technicians repair every major brand across Columbia and the Midlands, and we've been family-owned since 2011. Our residential diagnostic fee is $89, waived when you go ahead with the repair, and you'll get a firm price before any work begins — plus in-person help with financing for bigger jobs. Emergency service is available 24/7. Learn more about AC repair, call (803) 781-4357 or request service online.