5 Common Reasons Your Split System is Not Cooling

When your split system air conditioner stops cooling effectively, it can quickly turn your comfortable home into an uncomfortable space.

Whether you’re dealing with sweltering summer heat or simply trying to maintain a pleasant indoor temperature, a malfunctioning unit can disrupt your daily life. The good news is, most cooling issues are caused by common problems that can often be fixed with some basic troubleshooting or professional help.

In this blog, we’ll explore five of the most frequent reasons your split system might not be cooling as expected. From dirty filters to refrigerant leaks, understanding these issues can help you pinpoint the problem and get your air conditioner back to working efficiently.

Let’s take a detailed look into the top five culprits behind a lack of cool air from your split system.

1. Refrigerant Leaks

Refrigerant is the substance responsible for absorbing heat from your home and releasing it outside, which allows your split system to cool the air. When there’s a leak, your air conditioner doesn’t have enough refrigerant to complete this process efficiently.

As a result, you’ll notice that your split system struggles to cool your home, and you might even feel warm air blowing from the vents.

Refrigerant leaks are not only bad for your system’s cooling performance, but they can also lead to higher energy bills as your unit works harder to compensate for the loss. Additionally, running a system low on refrigerant can cause further damage to key components like the compressor, leading to costly repairs.

Unfortunately, refrigerant leaks aren’t something you can fix on your own. It’s important to call a professional heating, ventilation and air conditioning (HVAC) technician who can locate the leak, repair it, and recharge the system with the proper amount of refrigerant. Catching and fixing a refrigerant leak early can save you from bigger headaches down the line.

A woman cleans air filters from an air conditioner

2. Clogged Air Filters

One of the most common reasons your split system isn’t cooling effectively is a clogged air filter. Over time, dust, dirt and other debris accumulate in the filter, blocking airflow and reducing your system’s efficiency.

Here’s how clogged air filters can impact your cooling:

Reduced airflow: When the filter is clogged, it restricts the amount of air that can pass through, which makes it harder for your system to cool your home.
Increased energy consumption: A system with clogged filters has to work harder to circulate air, leading to higher energy bills.
Poor indoor air quality: Dust and allergens trapped in the filter can be recirculated into your home, reducing air quality and aggravating allergies.
Shortened system lifespan: Overworking your system due to blocked filters can cause it to wear down faster, leading to potential breakdowns and expensive repairs.

To keep your split system running smoothly, it’s important to check and clean or replace your air filters regularly − usually every 1 to 3 months, depending on usage.

3. Blocked or Leaking Ducts

Blocked or leaking ducts are a common cause of inefficient cooling in split systems. When the air can’t flow properly through the ducts, it can’t reach all the rooms in your home, leaving some areas too warm.

Here are some key issues related to duct problems:

Blockages: Dirt, dust, or debris can build up inside the ducts, restricting airflow and making it difficult for cool air to circulate throughout your home.
Leaks: Small holes or cracks in the ducts can cause cool air to escape before it even reaches your living space, reducing overall cooling performance.
Unbalanced airflow: If the ducts are poorly designed or installed, some rooms may not receive enough cool air, leading to uneven cooling across your home.
Increased energy consumption: When cool air is lost through leaks or blockages, your split system has to work harder to maintain the desired temperature, leading to higher energy bills and a strain on your HVAC system.

Regular duct inspections and cleaning can help prevent blockages, while sealing any leaks ensures your system cools your home efficiently and effectively.

4. Dirty Condenser Coils

Your split system’s condenser coils play a key role in cooling your home. They’re responsible for releasing the heat that’s absorbed from inside your house to the outside. When these coils get dirty, typically from dust, dirt, or debris, they can’t effectively transfer heat. This causes your system to work harder, but with less efficiency, which leads to poor cooling performance.

When your condenser coils are coated in grime, they struggle to expel heat, which forces your air conditioner to run longer and use more energy, often without delivering the cool air you need. You might also notice an increase in your energy bills, as the system becomes less efficient.

To prevent dirty condenser coils from hindering your cooling, regular maintenance is essential. Cleaning the coils once or twice a year helps ensure your split system runs smoothly.

If you’re not comfortable cleaning the coils yourself, hiring a professional technician can ensure they’re properly maintained and keep your system cooling efficiently throughout the year.

A man changes the temperature on the AC thermostat

5. Thermostat Issues

Sometimes, the reason your split system isn’t cooling could be as simple as a thermostat issue. When the thermostat isn’t working correctly, it can prevent your air conditioner from maintaining the desired temperature.

Here are some common thermostat problems that can affect your cooling:

Incorrect settings: Ensure the thermostat is set to “cool” mode and that the temperature is set lower than the current room temperature. It’s easy to accidentally switch it to “fan” or “heat” mode.
Thermostat placement: If the thermostat is installed in a warm spot, such as near a window or in direct sunlight, it might sense the wrong temperature, causing the system to overheat or not cool enough.
Faulty thermostat: Over time, thermostats can wear out or malfunction, leading to inaccurate temperature readings or causing the system to cycle on and off frequently.
Outdated model: Older thermostats may not work as efficiently with newer systems. Upgrading to a programmable or smart thermostat can help improve cooling control.

If you suspect a thermostat issue, it’s worth checking these points before calling a technician.

Keep the Cool Breeze Flowing

In most cases, when your split system isn’t cooling, the issue is caused by something simple, like a clogged filter or a thermostat setting that needs adjusting.

However, more serious problems like refrigerant leaks or blocked ducts may require professional attention. Regular maintenance is key to keeping your split system running efficiently and avoiding these common issues. By staying on top of things like cleaning the air filters, inspecting the condenser coils, and checking the thermostat, you can ensure that your system continues to cool your home as it should.

If you’re unsure about any of the potential issues, or if the problem persists after troubleshooting, it’s always a good idea to contact an HVAC professional. They can accurately diagnose and fix any underlying issues, ensuring your split system runs smoothly and keeps your home comfortable year-round.

Please note: This information is provided for advice purposes only. Regulations differ from state to state, so please consult your local authorities or an industry professional before proceeding with any work. See our Terms & Conditions here.