When the Phoenix sun is blazing, the last thing you need is an air conditioner that’s not cooling your home effectively. Air conditioners are a lifeline for many Arizonians, especially during the intense summer heat. However, like any other appliance, they can malfunction or underperform, leaving you sweating and searching for answers. In this comprehensive guide, we will explore the common reasons why your air conditioner is not cooling and how Merlin’s AC & Plumbing, a trusted provider of HVAC and plumbing repair services, can help you restore your home’s comfort. So, if you find yourself asking, ‘why is my air conditioner not cooling?’, you’re in the right place. Let’s dive in and uncover the causes behind this common AC issue.

Understanding the Basics of Air Conditioning

Before we dive into the reasons why your air conditioner may not be cooling your home effectively, let’s take a brief detour into the world of HVAC to understand how this machine works. After all, as the old saying goes, knowledge is power.

How Does an Air Conditioner Work?

At its core, an air conditioner is a champion of heat transfer. It works tirelessly to extract the hot air from your home and replace it with cool, refreshing air. This process is facilitated by two units: the indoor unit and the outdoor unit.

Inside the indoor unit, you’ll find an evaporator. This component allows the refrigerant—an essential cooling fluid—to vaporize and, in the process, extract heat. The cooled air is then released back into your house, providing that much-needed relief from the Arizona sun.

Meanwhile, the outdoor unit houses a compressor, a coil, and a fan. The compressor acts as a highway for the refrigerant, guiding it through the entire system. As the refrigerant flows, it’s pressurized, then transported through the condenser coil. The fan steps in, sending atmospheric air through the loop and reducing its temperature to create that cooler air we all crave on sweltering summer days.

Remember, your air conditioner isn’t just about circulating cold air; it’s about dispersing the heat from your home.

Importance of Regular AC Maintenance

Regular maintenance of your air conditioner is as crucial as getting your car serviced. It increases the longevity of your system and saves you from the cost of avoidable repairs and unplanned replacements. Think of it as a small investment for long-term comfort.

Regular maintenance can be as simple as checking if your thermostat is outdated or ensuring unrestricted airflow in the air vents. Other practices include unclogging your drain line, replacing the air filter about four times a year, and ensuring the outdoor condenser unit is unblocked. Also, keep an eye on your refrigerant lines. If they’re not insulated, call a professional immediately.

These are simple DIY tips that can help maintain your air conditioning system. However, some maintenance practices require the expertise of a professional. Recognizing when to call in the pros can save you from damaging your system and ensure it runs smoothly for as long as possible.

In the end, remember that, like any other machine, your air conditioner has a lifespan. No matter how well you maintain it, eventually, it will need to be replaced. Regular maintenance, however, can help you get the most out of your system before it’s time to retire it.

Now that we’ve covered the basics and the importance of regular maintenance, let’s move on to the common issues that could be affecting your AC’s cooling ability.

AC repair

Common Issues Affecting Your AC’s Cooling Ability

Having a well-functioning AC system is crucial in the sweltering heat of Phoenix, AZ. But what if you’ve been cranking up the AC and your home still feels like a sauna? Here are some common issues that could be affecting your AC’s cooling ability.

Incorrect Thermostat Settings

The first thing to check is your thermostat. A minor malfunction can cause major cooling problems. If your AC is short cycling or your home’s temperature doesn’t match the thermostat setting, you may have a faulty thermostat. Incorrect thermostat settings can cause your AC to work overtime without effectively cooling your home. Make sure your thermostat is set to cool, not heat. If your thermostat requires batteries, replace them with new ones. Some of the newer smart thermostats can benefit from a hard restart.

Clogged or Dirty Air Filters

A common culprit in AC performance issues is clogged or dirty air filters. Dirt, pet hair, pollen, and dust can block the flow of air, causing your AC to work harder without effectively cooling your space. Regularly cleaning and changing the filters every three months can help prevent this issue.

Blocked or Dirty Condenser Unit

Your condenser unit plays a crucial role in expelling heat away from your home. However, if it’s blocked by debris or dirt, it can’t do its job properly. Regularly cleaning and inspecting your condenser unit can help ensure optimal performance.

Damaged or Malfunctioning Heat Pump

The heat pump is the heart of your AC system, circulating refrigerant between the indoor and outdoor units. If it’s damaged, your entire system can’t cool your home effectively. If you suspect your heat pump is malfunctioning, it’s best to call in a professional.

Frozen Evaporator Coil

The evaporator coil absorbs heat from your home so it can be expelled outside. However, if it gets too cold, it can freeze over, leading to low airflow and ineffective cooling. This can occur due to low refrigerant levels, dirty air filters, or blocked airflow.

Refrigerant Leaks

Refrigerant leaks are another common reason why your AC might not be cooling your home efficiently. If there’s a leak in the system, there won’t be enough refrigerant to absorb the heat, causing your AC to struggle. Remember, refrigerant is a chemical that should be handled by professionals due to its potential impact on the environment and health risks.

Improperly Sized Air Conditioner for Your Space

Lastly, an improperly sized air conditioner can lead to cooling issues. If your AC is too small for your space, it will struggle to cool your home effectively. Conversely, an oversized AC will cycle on and off frequently, leading to inefficient operation and increased wear and tear.

Understanding these common issues can help you identify potential problems early and seek professional help when necessary. Regular maintenance can also prevent many of these issues, ensuring your AC keeps your home cool and comfortable all summer long.

Sun heat effect

The Impact of External Factors on Your AC’s Performance

While internal mechanics play a significant role in your AC’s performance, external factors can also negatively affect your system’s ability to cool your home. Here are some often overlooked influences that can impact your AC’s cooling efficiency.

Heat from Nearby Appliances

Appliances like TVs, laptops, and lamps can generate substantial heat, which can trick your thermostat into thinking that your home is hotter than it actually is. This can lead to your AC working in overdrive, leading to inefficiency and potential breakdowns. It’s crucial to ensure there’s sufficient distance between your thermostat and any heat-generating appliances to prevent this issue.

Excessive Heat from the Sun

We install air conditioning units to escape the scorching Arizona heat. However, the sun’s rays can also adversely affect your AC’s performance. If the sun is shining directly on your thermostat, it could cause the system to work harder than necessary. On particularly hot days, it’s advisable to draw your shades to reduce the heat load in your home. This can help your AC system operate more efficiently and maintain a comfortable indoor temperature.

Leaking Air from Ducts or Windows

Ductwork is essential for distributing cool air throughout your home. However, if your ducts are damaged, whether by pests or improper installation, they could be leaking cool air. This means your AC has to work harder to cool your home, leading to decreased efficiency and increased energy bills. Similarly, windows that aren’t properly sealed can also let out cool air and let in warm air, further exacerbating the problem. Regular inspection of your ductwork and windows can help you catch and address these issues early.

Dirty or Blocked Registers

Just like filters, your AC’s registers can accumulate dirt and dust over time, affecting airflow and forcing your AC to work harder. This not only increases your energy bills but also fails to effectively cool your home. Regularly cleaning your registers can help prevent this issue. Additionally, ensure that your registers are not blocked by furniture or other objects, as this can severely hamper airflow.

By understanding the impact of these external factors, you can take proactive steps to keep your AC running at maximum efficiency. Remember, regular maintenance is key to keeping your AC in top shape and your home comfortably cool. When in doubt, don’t hesitate to call a professional HVAC service like Merlin’s AC & Plumbing. We offer prompt, reliable, and transparent service to homeowners in Phoenix, AZ.

AC service technician

How Merlin’s AC & Plumbing Can Help

After a sweltering day in the Phoenix sun, there’s nothing worse than returning to a home where your air conditioner is not cooling. At Merlin’s AC & Plumbing, we understand that these problems can’t wait. That’s why we’re committed to providing fast, efficient, and effective solutions to restore your comfort and peace of mind.

Same-Day Service for Urgent AC Issues

Time is of the essence when your AC is not cooling your home properly. The discomfort increases with every passing hour. That’s why we offer same-day service for urgent AC issues. Whether it’s a malfunctioning heat pump, a refrigerant leak, or a frozen evaporator coil, our team of experienced technicians is ready to provide rapid and reliable service to get your AC back up and running.

Upfront Pricing for All AC Repairs and Maintenance

There’s nothing worse than being hit with unexpected costs when you’re already dealing with a malfunctioning AC system. At Merlin’s AC & Plumbing, we believe in transparency. That’s why we provide upfront pricing for all our AC repairs and maintenance services. No hidden fees, no surprise charges, just honest and fair pricing. You’ll know exactly what you’re paying for before we start any work, allowing you to make informed decisions about your AC repair needs.

100% Satisfaction Guarantee on All Services

We’re not just in the business of fixing AC systems; we’re in the business of ensuring your comfort and satisfaction. We stand behind the quality of our work, offering a 100% satisfaction guarantee on all services. Our team of licensed technicians won’t stop until your AC is cooling your home effectively and efficiently. We value your trust, and we’ll go above and beyond to ensure we’re your go-to choice for all your AC and plumbing needs in Phoenix, AZ.

In the face of an AC crisis, you can count on Merlin’s AC & Plumbing for swift, transparent, and satisfactory service. Let us tackle your cooling challenges head-on, providing you with the comfort you deserve.

AC maintenance

Preventive Measures and Regular Maintenance

Your air conditioning system is not unlike a car; it requires regular check-ups and maintenance to run smoothly and efficiently. Neglecting these preventive measures can lead to costly repairs, reduced system lifespan, and an uncomfortable living environment. Don’t wait until you’re sweating in the heat of summer to address potential issues with your AC.

Importance of Regular Filter Changes

Do you know how often you should change your air filters? The answer depends on several factors, including the type of filter you’re using, the level of air pollution in your area, and the number of people and pets in your home. However, a good rule of thumb is to check your air filters every month and replace them every three months. If you have pets, allergies, or live in an area with high levels of pollution, you may need to replace them more frequently. Regular filter changes not only improve indoor air quality by removing dust, mold, pet dander, and other pollutants but also ensure your AC system runs efficiently, reducing energy bills and extending system lifespan.

Benefits of Regular AC Tune-Ups

In addition to regular filter changes, scheduling regular tune-ups with a professional HVAC technician is paramount to ensuring your AC system’s optimal performance. Regular maintenance helps identify and address potential issues before they turn into major problems, saving you money in the long run. Plus, a well-maintained AC system ensures consistent comfort throughout your home, preventing hot and cold spots. Regular maintenance also reduces the risk of unexpected breakdowns and keeps your family safe by identifying worn-out components, loose connections, or other issues that could lead to system failure.

How to Properly Size an AC Unit for Your Space

Finally, it’s crucial to have an AC unit that’s properly sized for your space. An oversized unit may lead to short cycling, causing increased wear and tear and decreased efficiency. Conversely, an undersized unit may struggle to cool your home effectively, especially on hot days. To determine the right size unit for your home, it’s best to consult with a professional HVAC technician who’ll consider the size of your home, the number of occupants, and other factors.

By implementing these preventive measures and committing to regular maintenance, you can keep your AC system running efficiently and comfortably all year round. Remember, the key to a cool, comfortable home is not just in dealing with issues as they arise, but in preventing them from happening in the first place.


When it comes to the comfort of your home, there’s no room for compromise. A well-functioning air conditioner is a critical component of that comfort, especially in the scorching heat of Phoenix, AZ. So, when your AC system fails to cool your home adequately, it can throw your entire day into chaos. But understanding the common reasons why your air conditioner is not cooling can equip you with the knowledge to troubleshoot minor issues on your own and to know when it’s time to call in the experts.

From improper thermostat settings and dirty filters to external heat sources and refrigerant leaks, several issues can impede your air conditioner’s performance. Regular maintenance, including timely filter changes and AC tune-ups, can go a long way in preventing these problems and ensuring your AC system operates at its best. But even with the best maintenance, issues can still arise.

When they do, you can count on Merlin’s AC & Plumbing to provide prompt, reliable service. Our commitment to upfront pricing and a 100% satisfaction guarantee means you can trust us to deliver high-quality solutions without any surprises. And with our same-day service for urgent AC issues, you won’t have to endure the discomfort of a hot home for long.

In the end, the key to a cool, comfortable home lies in a well-maintained and efficient air conditioner. By understanding common AC issues and how to prevent them, you can enjoy the cool, refreshing air all summer long. And when issues do arise, remember that Merlin’s AC & Plumbing is just a call away, ready to restore the comfort of your home. Remember, the key to a cool, comfortable home is not just in dealing with AC issues as they arise, but in preventing them from happening in the first place.

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