When the summer heat in East Tennessee rises, the last thing you want is for your air conditioner to stop working. A malfunctioning AC unit can quickly turn your comfortable home into a sweltering space. If you've been wondering why your air conditioner isn’t cooling properly, you're not alone. Here are the top 7 reasons your air conditioning system might be underperforming — and what you can do to fix it.

1. Dirty Air Filters

One of the most common reasons an air conditioner fails to cool properly is a dirty air filter. Over time, dust, dirt, and debris build up and block airflow, making your unit work harder to cool your home.

What to do:Check your air filter monthly and replace it every 1-3 months, depending on usage and household factors like pets or allergies. A clean filter ensures proper airflow and helps your AC run efficiently.

2. Low Refrigerant Levels

Refrigerant is what your AC system uses to remove heat from your home. If levels are low due to a leak or improper installation, your AC won't be able to cool the air effectively.

What to do:Contact a licensed HVAC technician to check for leaks and recharge the refrigerant. Attempting to do this yourself is not only unsafe but also illegal without proper certification.

3. Thermostat Issues

Sometimes the problem isn’t with the AC unit itself but with the thermostat. A malfunctioning thermostat can misread the indoor temperature and fail to signal the AC to start or stop at the right times.

What to do:Make sure your thermostat is set to "cool" and not "fan" or "heat." Consider upgrading to a programmable or smart thermostat for better efficiency and control.

4. Blocked or Leaky Ducts

Air ducts are responsible for distributing cool air throughout your home. If they are blocked by debris or leaking, cooled air can escape before reaching the rooms.

What to do:Have a professional inspect and seal your ductwork. Duct cleaning may also be necessary if there is excessive buildup of dust or mold.

5. Dirty or Frozen Evaporator Coils

The evaporator coil absorbs heat from your home. If it’s dirty or frozen, it can’t effectively do its job, and your AC system will struggle to cool your home.

What to do:Turn off your AC and let the coils thaw if they are frozen. Schedule regular maintenance to have the coils cleaned professionally.

6. Faulty Compressor

The compressor is the heart of your AC system. It circulates refrigerant between the indoor and outdoor units. If it fails, the entire cooling process is disrupted.

What to do:A faulty compressor requires a professional HVAC technician for diagnosis and replacement. This is a complex and often costly repair.

7. Inadequate AC Unit Size

If your air conditioner is too small for your space, it won’t be able to keep up with cooling demands. Conversely, an oversized unit can short-cycle, turning on and off too quickly without dehumidifying properly.

What to do:Have a load calculation done by a certified HVAC technician to determine the right size unit for your home. Proper sizing ensures efficiency and comfort.

Tips for Preventing AC Problems

  • Schedule Annual Maintenance: Regular HVAC tune-ups catch issues early.
  • Keep Vents Clear: Don’t block vents with furniture or curtains.
  • Use Ceiling Fans: They help distribute air more evenly.
  • Install a Smart Thermostat: Automate temperature adjustments and save energy.
  • Shade Your Outdoor Unit: Reduce the strain on your AC by protecting it from direct sunlight.

When to Call the Pros

If you've tried these tips and your air conditioner still isn't cooling, it's time to call the professionals. At Advanced Heat AC & Plumbing, we provide expert air conditioning repair and maintenance throughout East Tennessee. Our trained HVAC technicians can diagnose the problem quickly and restore your comfort in no time.

We offer comprehensive HVAC services including:

  • AC diagnostics and repair
  • Refrigerant leak detection
  • Ductwork inspection and sealing
  • Thermostat upgrades and replacements

Don't suffer in the heat. Contact us today to schedule service or learn more about our cooling solutions.

Frequently Asked Questions About AC Cooling Issues

What temperature should I set my thermostat to in summer?

Set your thermostat to 78°F when you’re home. Raise it when you’re away to save energy.

How often should I replace my air filter?

Replace your air filter every 1-3 months depending on usage and whether you have pets or allergies.

How can I tell if my refrigerant is low?

Signs include warm air blowing from vents, hissing noises, and ice on the evaporator coils.

Is it safe to clean my own evaporator coils?

While basic cleaning may be safe, it’s best to have a professional handle coil cleaning to avoid damage.

Can a thermostat really affect cooling performance?

Yes, if the thermostat is faulty or placed in a poor location, it can misread the temperature.

How do I know if my ductwork is leaking?

Signs include inconsistent room temperatures, higher energy bills, and visible dust buildup near vents.

How long should a central AC system last?

With proper maintenance, a central AC system can last 12-15 years.

What does short-cycling mean?

Short-cycling is when the AC turns on and off frequently without completing a cooling cycle. This can wear out the system.

Can ceiling fans help my AC cool better?

Yes, they help distribute cool air more evenly, allowing you to raise your thermostat setting.

Should I repair or replace an old AC unit?

If your system is over 10 years old and needs frequent repairs, replacement may be more cost-effective.

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