Lexington, SC AC Repair: Why Your AC Runs But Won’t Cool

Estimated Read Time: 9 minutes

When your AC is running but not cooling, frustration rises as fast as the Midlands heat index. Here are the top reasons your system blows warm air, what you can check safely, and when to call a pro. You’ll also learn how to prevent the next breakdown and lower bills. If you need help now, our 24/7 team in Columbia can get you comfortable fast, often the same day, with free estimates and no after-hours fees.

1) Dirty or clogged air filter

A packed air filter chokes airflow, so your AC runs longer without delivering cool air. Low airflow can also cause evaporator coils to freeze. When ice forms, the system may hum along but barely cool your home.

What to do now:

1. Turn the system off to thaw icy coils, if present.
2. Replace a 1-inch filter every 30 to 60 days. High-efficiency homes or pet households may need monthly changes.
3. Check that the filter’s arrow points toward the blower.

When to call a pro:

• You see ice on the indoor coil or refrigerant lines after changing the filter.
• Airflow stays weak room to room. That could indicate blower or duct issues.

Prevent it:

• Set calendar reminders for filter changes.
• During a professional tune-up, techs verify airflow, clean components, and confirm static pressure so rooms cool evenly.

Review callout:

• “Rusty and his partner were great! They not only fixed my AC within a couple hours of calling but they made recommendations to prevent this in the future and services they offer!”

2) Thermostat missettings or sensor issues

Thermostats are small but mighty. A wrong mode or fan setting can trick you into thinking the AC is failing.

Quick checks:

1. Ensure Cool mode is selected and the setpoint is at least 5 degrees below room temperature.
2. Set the fan to Auto, not On. The On setting can blow room-temperature air between cycles.
3. If you have a smart thermostat, confirm schedules and geofencing are correct.

Sensor or placement problems:

• A thermostat in direct sun, near a lamp, or above a supply register can read falsely high or low, causing short or long cycles and poor comfort.
• Miscalibrated sensors lead to drifting temperatures and wasted energy.

Energy fact:

• The U.S. Department of Energy recommends 78°F for summer cooling when you are home. This helps comfort and utility costs without overworking the system.

When to call:

• Frequent overshooting, unresponsive controls, or wiring issues. A licensed tech can test sensors, wiring, and staging to restore accurate control.

Review callout:

• “Nick F. was professional, courteous and responsive on short notice. He arrived quickly and immediately fixed an ongoing AC issue. Appreciate it very much.”

3) Low refrigerant or a leak

Your AC relies on precise refrigerant charge to absorb and move heat. If there is a leak, the system may still run but cool poorly, often with longer cycles, warm supply air, hissing sounds, or ice on the indoor coil.

Safety and compliance facts:

• Only EPA Section 608–certified technicians can handle refrigerants. Proper leak detection and repair protect performance and the environment.
• Many manufacturers require documented, professional service to keep warranties valid.

What to expect from a pro:

1. Visual inspection for oil staining at joints and coils.
2. Electronic or nitrogen pressure testing to pinpoint the leak.
3. Repair of the leak, evacuation, and recharge to the exact specification.
4. System performance verification, including superheat/subcool readings.

Why this matters in Columbia:

• High summer humidity around the Congaree and Lake Murray makes proper charge critical. Undercharged systems struggle to remove moisture, so you feel clammy even when the thermostat shows the right number.

Review callout:

• “Unbeatable HVAC service! I was concerned that my very old unit wasn’t repairable. Nick is the best! He immediately identified the problem and took measures to acquire the needed parts! The repair was completed promptly and at a very reasonable price!”

4) Dirty coils or a blocked outdoor unit

Heat must move out of your home. If the condenser coil outside is caked with pollen, grass clippings, or lint, heat rejection stalls and cooling capacity drops.

Homeowner steps:

1. Power off at the disconnect and main panel before any cleaning.
2. Gently rinse the coil from the inside out with a garden hose. Avoid bending fins.
3. Keep 2 to 3 feet of clearance around the unit. Trim bushes and remove debris.

Why professional cleaning helps:

• Techs use coil-safe cleaners, straighten bent fins, check the condenser fan motor, and confirm amperage and capacitor health. They also measure temperature split to verify results.

Related issues:

• A failing condenser fan or weak capacitor can mimic a dirty coil problem. You may hear the compressor running while the fan sits still, leading to overheating and poor cooling.

Review callout:

• “Once again, Kaminer saves our day. Michael cleaned the coils, got the compressor back in working order, and my house cooling down within an hour. Same day service, no less.”

5) Electrical problems, capacitors, or blower issues

Your system can hum along with lights on the thermostat yet deliver warm air if an electrical component has failed.

What you can check safely:

1. Confirm the indoor and outdoor breakers are on. Reset once if tripped.
2. Look for a blocked return grille or closed supply vents.
3. Listen for the blower. If the outdoor unit runs but the indoor blower does not, cooling will feel weak.

Common component failures a pro should handle:

• Run/start capacitors that no longer hold a charge.
• Shorted contactors or pitted relay points.
• Loose or corroded wiring, especially on older systems.

Why speed matters during heat waves:

• Prolonged overheating can damage compressors. A quick diagnosis protects the most expensive part of your system and can save you thousands.

Review callout:

• “Today Chris Conroy with Kaminer Heating and Cooling came to our home to fix our AC unit. Chris was very professional and helpful. He made it out for a same day service and had us back up and running in no time!”

6) Clogged condensate drain or tripped safety switch

If the drain line clogs, water can back up and trigger a float safety switch. The blower or outdoor unit may keep running intermittently, but cooling shuts down to prevent water damage. You will feel warm air and may notice a full drain pan or water near the air handler.

Quick homeowner steps:

1. Turn the system off.
2. Clear the outside drain with a wet/dry vacuum for 2 to 3 minutes.
3. Pour a cup of distilled white vinegar into the cleanout port to slow algae growth.

When to call:

• Repeated clogs, no visible cleanout, or secondary drain pan sensors tripping. Pros will flush the line, inspect the trap, and verify pitch and safety switch operation. They can also add an access tee for easier seasonal maintenance.

Review callout:

• “Troy has been our hero this summer! He pinpointed the problems and fixed them quickly. We’ve had no reoccurring issues!”

7) Ductwork leaks, poor airflow, or short cycling

Leaky or undersized ducts waste cooled air into attics and crawlspaces. You pay for cooling that never reaches rooms. Short cycling, often from airflow issues or an oversized unit, leaves the house humid and uneven.

Warning signs:

• Dusty rooms, hot spots, or weak airflow at distant registers.
• High bills and long run times, even after a filter change.

What pros do:

1. Measure static pressure and temperature rise/drop across equipment.
2. Inspect duct joints, plenums, and boots for gaps and tape failures.
3. Seal with mastic or approved materials and recommend right-sized returns.
4. Balance airflow to critical rooms like bonus spaces over garages that heat up fast in Midlands afternoons.

Complementary upgrades:

• Proper return sizing, smart thermostat optimization, and high-MERV filtration or HEPA bypass systems can improve comfort and indoor air quality.

Review callout:

• “Every single employee from Kaminer was extremely professional, friendly, and helpful. They diagnosed the problems, explained everything, and within 2 weeks we are now up and running with a brand new A/C and completely repaired duct work.”

When to repair vs. replace

If your AC is over 12–15 years old, needs major components like a compressor, or struggles to dehumidify during typical Columbia humidity, a replacement may lower lifetime costs. New systems can cut cooling energy use by 20 to 40 percent when properly sized and installed.

Professional guidance you can expect:

1. Load calculations, not guesswork, to size equipment.
2. Duct evaluation so new equipment is not starved for airflow.
3. Options for efficiency, filtration, and financing.

Local advantage:

• As a third-generation company serving our region since 1956, we know how swampy July evenings feel in West Columbia and Irmo. We match equipment and setup to real Midlands conditions.

Prevent the next no-cool call with maintenance

Regular tune-ups catch small issues early. Our spring maintenance includes:

• Cleaning or replacing filters to protect airflow and efficiency.
• Inspecting electrical components to prevent surprise failures.
• Checking refrigerant levels and verifying there are no leaks.

Pro tip checklist between visits:

1. Replace filters routinely.
2. Keep 2 to 3 feet of clearance around the outdoor unit.
3. Seal air leaks at doors and attics to reduce load.
4. Use ceiling fans to help you feel cooler at 78°F settings.

Hard facts that protect your comfort:

• Annual professional maintenance is recommended at least once a year, ideally in spring, to prepare your system for peak heat.
• Kaminer provides a true 24/7 service line with no after-hours fees, backed by a 100% satisfaction guarantee.

Special Offer: Free Estimate on AC Repair in Columbia, SC

Save on diagnostics and get a clear repair plan today. Free estimate for air conditioning services in Columbia, SC. Call (803) 888-4115 to request your free estimate before 2026-04-01. Same-day emergency response available with no after-hours fees.

Frequently Asked Questions

Why is my AC running but not cooling at all?

Common causes include a dirty filter, thermostat missettings, low refrigerant, or a clogged condensate drain. Check the filter and thermostat first. If airflow is weak or you see ice, schedule professional service.

Is it safe to keep running the AC if it is not cooling?

Turn it off. Running with low airflow or low refrigerant can ice coils and overheat the compressor. Powering down protects the equipment and can prevent a costly repair.

How often should I change my AC filter in Columbia, SC?

Check monthly and replace every 30 to 60 days for 1-inch filters. Homes with pets, renovations, or allergy concerns may need more frequent changes or a higher-MERV solution.

What temperature should I set in summer for comfort and savings?

Many experts recommend 78°F when you are home. Use ceiling fans to feel cooler and adjust a few degrees higher when you are away to reduce energy costs.

Do you service all AC brands and offer emergency repairs?

Yes. We service all brands, offer true 24/7 emergency response, and never charge after-hours fees. Call (803) 888-4115 for immediate help in the Columbia area.

Final Takeaway

If your AC is running but not cooling, start with safe checks, then bring in a pro to protect your system and restore comfort. From filters and thermostats to refrigerant and ductwork, we fix the real cause fast. Kaminer Heating And Cooling has served Columbia since 1956 with 24/7 service and free estimates.

Ready for fast, reliable AC repair?

Call Kaminer Heating And Cooling at (803) 888-4115 or visit https://www.kaminerhac.com/ to schedule now. Mention our free estimate for air conditioning services in Columbia, SC, available through 2026-04-01. Same-day emergency response. No after-hours fees. Serving Columbia, Lexington, Irmo, West Columbia, Blythewood, and nearby neighborhoods.

About Kaminer Heating And Cooling

Kaminer Heating And Cooling is a third-generation, family-owned HVAC company serving the Columbia, SC area since 1956. We deliver fast, code-compliant service with a 100% satisfaction guarantee and an A+ BBB rating. Our technicians receive continuous training and service all brands. We offer true 24/7 emergency response with no after-hours fees, free estimates, and financing options. From precise repairs to maintenance plans, we keep Midlands homes comfortable year-round.