AC Not Cooling in Snellville? 7 Common Causes & What to Do Next

It is a familiar frustration for Snellville homeowners: You walk inside expecting relief from the 90°F Georgia heat, only to find your home feels sticky and warm. You put your hand to the vent, and while the air is blowing, it certainly isn't cold.

At DGL Heating & Air Conditioning, we have answered emergency "AC not cooling" calls across Gwinnett County from the historic district to the neighborhoods near Briscoe Park for over a decade. We know that in our climate, a broken AC isn't just an inconvenience; it’s an emergency.

The good news? Most cooling issues have identifiable causes. Some are simple fixes you can handle yourself, while others require a certified expert. Knowing the difference can save you time, money, and stress.

Below, we break down the 7 most common reasons your system might be struggling (specifically the "ac running but not cooling" scenario) and exactly what to do about them.

Immediate Safety & Basic Checks (Do These First!)

Before we troubleshoot, prioritize your safety. If you ever smell burning, hear loud grinding noises, or see smoke, turn your system OFF immediately at the thermostat and breaker, then call us.

If the system sounds normal but just isn't cooling, check these two things first:

1. Check Your Thermostat Settings

It sounds simple, but we frequently solve "emergencies" just by adjusting a setting.

• Mode: Ensure it is set to COOL, not "FAN" or "HEAT."
• Fan: Set it to AUTO. If it is set to "ON," the fan blows continuously even when the compressor is off, making the air feel humid.
• Pro Tip: Older thermostats often lose calibration in our humidity. If yours is 10+ years old, it may be misreading the room temperature.

2. Inspect the Circuit Breaker

Go to your electrical panel and check the breaker labeled "AC" or "HVAC."

• Is it tripped? The switch will be in the middle position.
• The Fix: Flip it completely OFF, then back ON.
• Warning: If it trips again immediately, do not reset it. You likely have an electrical short. Call a professional.

AC Running But Not Cooling? The 7 Most Likely Culprits

If your settings are correct, one of these 7 issues is likely the cause. We have organized them by how common they are in Snellville homes.

1. A Dirty or Clogged Air Filter (Simple DIY Fix)

The Problem: Restricted airflow is the cause of cooling issues. A dirty filter acts like a mask over your system, forcing it to work harder and reducing its ability to cool the air.

What to Do:

• Locate your filter (usually in the return air vent).
• If it looks gray or clogged, replace it with a new MERV 8-11 filter.
• DGL Insight: During the peak summer season, check your filter every 30 days. Pollen and pet dander clog filters faster than you might expect.

2. Blocked or Dirty Outdoor Condenser Unit

The Problem: Your outdoor unit (the condenser) needs to "breathe" to release heat. If it is choked by tall grass, pine straw, or bushes, the heat gets trapped, and your home stays warm.

What to Do:

• Turn OFF the power at the outdoor disconnect box.
• Clear a 2-foot perimeter around the unit.
• Gently rinse the fins with a garden hose (avoid high-pressure washers, which can bend the fins).

3. Refrigerant Leak (Requires Professional Repair)

The Problem: Refrigerant (often called Freon) is the lifeblood of your AC. It circulates in a closed loop and should never "run out." If you are low on refrigerant, you have a leak.

Warning Signs:

• Hissing or bubbling noises near the unit.
• Ice forming on the copper refrigerant lines.
• Important: Simply adding more refrigerant without fixing the leak is illegal and ineffective. A certified technician must locate and seal the leak first.

4. Frozen Evaporator Coil

The Problem: When airflow is restricted (due to a dirty filter) or refrigerant is low, the indoor coil can get too cold and freeze into a block of ice. Ice acts as an insulator, blocking the cool air from entering your home.

Immediate Action: Turn your AC to FAN ONLY to help melt the ice. Call a professional to diagnose why it froze to prevent compressor damage.

5. Failing Compressor (Major Repair)

The Problem: The compressor is the heart of your system. If it fails, the fan might still run, but the air won't get cold.

Symptoms:

• A loud "humming" or buzzing sound from the outdoor unit.
• The system "hard starts" (shakes violently when turning on).
• DGL’s Approach: We perform a full diagnostic. If your system is over 12 years old, we may recommend you learn more about our AC replacement options to see if a new unit is more cost-effective.

6. Faulty Capacitor

The Problem: The capacitor is like a battery that gives your motors the jolt they need to start.

Common in Snellville: Our summer thunderstorms and power surges frequently weaken capacitors. Fortunately, this is usually a quick and affordable repair for a pro.

7. Ductwork Leaks

The Problem: In older homes, ductwork can separate or develop leaks, dumping your expensive cooled air into the attic instead of your living room.

Indicators: One room is freezing while another is hot, or you have higher-than-normal dust levels.

Troubleshooting Cheat Sheet: DIY or Call a Pro?

Not sure if you should grab a screwdriver or the phone? Use this quick guide to decide.

Symptom

Likely Cause

Action Required

Weak Airflow

Dirty Air Filter

DIY: Replace Filter

Unit Covered in Debris

Dirty Condenser

DIY: Clean with Hose

Thermostat Blank

Dead Batteries

DIY: Replace Batteries

Ice on Lines/Unit

Frozen Coil

Call DGL for Leak Diagnosis

Hissing Noise

Refrigerant Leak

Call DGL for Leak Repair

Loud Banging/Humming

Failing Compressor

Call DGL for Emergency Exam

Smell of Burning

Electrical Short

Call DGL Immediately

When to Call DGL Heating & Air Conditioning

If you have completed the basic checks and your home is still uncomfortable, it is time to call a professional.

Why Snellville homeowners choose DGL:

• Local Expertise: We understand how the local climate impacts different home builds, from slab foundations to crawlspaces.
• Certified Technicians: Our team is EPA-certified and background-checked.
• Transparent Pricing: We believe in no surprises. See our commitment to transparent pricing here.

Restore Your Comfort Today

Don't endure another day of sweltering heat in your own home. At DGL Heating & Air Conditioning, we combine technical expertise with genuine care for our neighbors in Snellville and throughout Gwinnett County.

Call us today at (678) 602-7424 for:

• Same-day diagnostic service
• Honest, upfront pricing
• Reliable local experts

Or visit us at 1975 Oak Rd SW to speak with our team. Let's get your cool comfort back—today.