Why Your AC Isn’t Cooling and How to Troubleshoot Like a Pro

Why Is My AC Not Cooling? Common Air Conditioning Issues and Their Solutions

There’s nothing more frustrating than enduring a sweltering hot day, only to find that your air conditioner isn’t doing its job. With temperatures soaring, the last thing anyone wants is a malfunctioning AC unit. To find relief, homeowners need to understand why their AC is not cooling effectively and what steps to take to remedy the issue. Loyal Home Services presents an in-depth guide exploring common problems and their corresponding solutions.

Why is AC not cooling | Common AC issues and Solutions - Woman using a handheld paper fan to cool herself

The Science Behind the Cold: How an AC Unit Operates

Before troubleshooting, it’s important to understand how an air conditioning system works. Essentially, an AC unit removes heat from the air inside a home and releases it outside, creating a cooler indoor environment. This process involves a series of interconnected components: the evaporator coil, condenser coil, compressor, and fan. If any of these parts malfunction, the entire cooling operation suffers.

Top Reasons Why AC is Not Cooling

Dirty or Clogged Filters: The Hidden Culprit

When an air filter becomes dirty or clogged, it restricts the airflow through the air conditioning system. This leads to several problems:

  • Reduced Efficiency: The AC unit must work harder to circulate air, resulting in decreased efficiency and higher electricity bills.
  • Poor Air Quality: A dirty filter can’t effectively trap pollutants, which means they circulate in the home, affecting indoor air quality.
  • System Strain: Over time, the extra work required to force air through a dirty filter can strain the system and shorten its lifespan.


Investing in high-quality air filters and adhering to a regular replacement schedule can make a significant difference. For homes with pets or allergy sufferers, specialized filters that capture more particles may be beneficial.

Incorrect Thermostat Settings: A Common Oversight

Sometimes, people forget to check the most straightforward things. If the thermostat is not set correctly, it can appear as if the AC unit is malfunctioning.

  • ‘Fan Only’: This setting circulates air but doesn’t cool it, making people think the AC isn’t working.
  • Wrong Temperature: If the set temperature exceeds the room temperature, the AC won’t turn on.


Ensure the thermostat is set to ‘Cool’ and the temperature is set to a comfortable level below the current room temperature. Also, ensure the thermostat’s batteries function, as a dead battery can cause setting malfunctions.

Low Refrigerant Levels: The Cooling Agent

Refrigerant is the lifeblood of an AC unit. Low levels often signify a leak in the system. This affects:

  • Efficiency: The AC unit has to run longer cycles to achieve the desired temperature.
  • Coil Freezing: Low refrigerant can lead to the evaporator coils freezing, worsening the problem.


If you suspect a refrigerant issue, this is not a DIY project. Contact an HVAC professional to recharge the refrigerant and fix any potential leaks.

Frozen Evaporator Coils: An Icy Dilemma

If the evaporator coils freeze, they can’t absorb heat effectively. This usually occurs due to:

  • Blocked Airflow: Often a result of dirty filters or obstructed air vents.
  • Low Refrigerant: This causes the coils to become too cold, leading to ice formation.


First, thaw the evaporator coils by turning off the AC unit and running the fan. If the problem persists, this is another situation where professional service is needed to diagnose and treat the underlying issue.

Leaking Ducts: The Invisible Drain

Leaking ducts can lose up to 30% of cooled air before it reaches the living areas. This leads to:

  • Inconsistent Temperatures: Some rooms may feel warmer than others.
  • Wasted Energy: The AC unit must run longer to achieve the desired temperature, leading to higher energy bills.


Inspect the ductwork in areas like the attic or basement for visible holes or cracks. Duct tape and mastic sealants are temporary fixes, but consider having your ductwork professionally sealed and insulated for a more permanent solution.

Electrical or Mechanical Failures

Sometimes, the issue could be more technical, like a failing capacitor, malfunctioning fan motor, or faulty wiring.


Electrical and mechanical problems require specialized knowledge. If you’ve ruled out simpler issues, it’s time to consult a professional.

Oversized or Undersized Units

If you suspect your AC unit size is inappropriate, consult an HVAC specialist for a detailed evaluation and recommendation.

By understanding these intricate details about why an AC is not cooling effectively, homeowners can make informed decisions by tackling simpler issues themselves or knowing when to call in the experts for more complex problems.

When to Call the Experts

If, after troubleshooting, you’re still asking, “Why is my AC not cooling?” it’s time to turn to experts for a comprehensive diagnosis and solution. Technicians can run a series of tests to identify the exact cause of the problem and provide appropriate repairs or replacements.

It’s important to fix the problem sooner rather than later for AC repairs, as delaying repairs can lead to more issues and the possible breakdown of your AC unit. Contacting experts like those at Loyal Home Services can bring comfort to your home and help you extend the life of your air conditioning unit.

Taking Control of Your Cooling Comfort

Understanding why an AC is not cooling can empower homeowners to take timely and effective action. Whether the problem lies in a dirty filter, malfunctioning thermostat, or more complex issues like low refrigerant levels or leaking ducts, being educated about the possible culprits and their solutions is the first step toward a cooler, more comfortable living environment. Armed with this knowledge, you can either handle straightforward fixes yourself or make an informed decision when it’s time to consult professionals, ensuring a quicker return to cool comfort.

Don’t let the heat disrupt your peace of mind. If your air conditioning system falls short of its primary cooling function, contact Loyal Home Services for an expert consultation and quick, reliable solutions. Your comfort is too important to compromise.


HVAC San Antonio, TX