10 Reasons Why Your AC Unit Isn’t Blowing Cool Air

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Air conditioners are vital in maintaining a healthy and comfortable living environment during the summer. They help in temperature and humidity regulation. However, air conditioners can experience problems like other mechanical systems. An example is when an AC unit isn’t blowing cold air. When this occurs, it is important to do something about it as soon as possible to prevent discomfort, health hazards, and expensive HVAC repairs. Keep reading to explore some of the causes of this common air conditioning problem.

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10 Reasons Your AC Unit Isn’t Blowing Cool Air

Here are several ways on what to check if your air conditioning system isn’t blowing cold air and how you can resolve the issue quickly:

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The Thermostat is Not Set Correctly

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Air conditioners only run when the room temperature exceeds the control setting. You need to make sure that the thermostat is set to “auto” and “cool” so that it turns on when necessary. First, confirm that the thermostat is set to the right temperature. The issue may sometimes happen if the thermostat is set to “heat” instead of “cool.”

A recent air conditioner service may have caused an accidental adjustment. If so, the thermostat must be switched to “heat” before setting it back to “cool.” Wait several minutes before checking the registers to see if cold air is blowing through.

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Dirty Air Filter

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You should check and change your air filters regularly. They can get severely clogged if you don’t do this. A clogged air filter can impede the airflow into your home. It can also damage the air conditioner’s other components, such as the evaporator coil.

This means the airborne particles cannot be filtered, and you may experience more dust, stuffiness, and a lack of cold air. Check your air filter once a month to prevent this. Clean and replace it as needed.

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Dirty or Clogged Condenser

A central air conditioner producing warm air can be because of a dirty or clogged condenser coil. The condenser fan sucks air through the condenser coil in the outdoor unit to remove the heat from your home during operation. However, the coil can get clogged with grass, dirt, and airborne particles blocking the airflow between fins. A dirty condenser unit can result in decreased energy efficiency. It can also cause compressor damage or system failure from overuse.

Remove grime and dust from the condenser coil. You can remove the debris with a soft brush, use a brush attachment to vacuum the coil, or gently hose it down. Call a certified HVAC technician to resolve this issue.

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Air Conditioner Refrigerant Leak

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A refrigerant leak is another cause your central AC system is not blowing cold air. Refrigerant, like R410a, is a crucial chemical coolant that facilitates cold air production from an air conditioner. It passes through the system’s indoor and outdoor coils, transitioning from liquid to gas. It also absorbs heat energy and humidity from the indoor air, releasing it outside your home.

The system’s refrigerant levels don’t usually reduce over time unless the refrigerant lines have a leak. The system won’t have enough refrigerant to produce cold air when this occurs. It is crucial to note that trying to repair a refrigerant leak on your own isn’t a good idea. The Environmental Protection Agency regulates this chemical, and certified experts are the only ones who can handle this chemical. An HVAC professional has the required tools to detect and repair refrigerant leaks. They can also top up the coolant so your home can stay cool and comfortable.

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Mechanical HVAC Problems

Air conditioners go through normal wear and tear as time passes. This can cause mechanical problems during its lifespan. Understanding how your air conditioner functions can help prevent potential mechanical issues at the onset.

Make sure that you check the thermostat and air filter. Contact an HVAC expert immediately if your air conditioner isn’t functioning normally or not running as expected. Book an inspection of your unit’s internal parts right away to make sure everything is in order.

Related Article: Why Is My Outside AC Unit Not Running But Inside Is?

HVAC Ductwork Leak

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A leak in the ducts means cold air will escape through the walls before it can reach the vents. This also implies that the same will happen to warm air during winter.

It can be difficult to diagnose a ductwork leak. Aside from the cold air you are paying for, you also have to spend a lot of money on repairs. Call a reliable HVAC professional for this issue.

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Evaporator Coil Issues

Air conditioners have an evaporator coil that removes the heat energy and humidity from the air. Low refrigerant levels in the system can cause the coil to freeze and frost to build up. This can also result in a lack of cold air production and increased energy bills.

If you aren’t a professional, it can be hard to access the evaporator coil. Let an HVAC expert handle this issue.

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Blocked HVAC Vents

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A blocked or obstructed vent can have the same impact as a restricted or clogged air filter. The vents bring air into the HVAC unit and circulate cold air throughout the house. Blockages can cause a problem with the air conditioner. 

An obstruction close to the vent means the room with the affected vent will feel warmer than other areas in your home. Contact a reliable cooling technician immediately to resolve the problem.

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Undersized AC Unit

Air conditioners are usually sized per their British Thermal Units or cooling capacity. The bad news is that an air conditioner that’s too small can cause problems like struggling to keep you cool as the temperature rises outside. As a result, the unit will work overtime, increasing the wear and tear in the system, and may need an early replacement.

One option is installing a ductless mini-split if you have an inadequate air conditioner. This can provide cooling to certain hot spots in your home. However, replacing your central air conditioner with a correctly sized unit is the best solution.

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Lack of Regular Air Conditioner Maintenance

The best preventative step to guarantee that your air conditioner cools your home effectively is to book annual maintenance services. Regular air conditioner tune-up will reduce energy bills and detect current and potential issues. 

Related Article: How Much Clearance Is Necessary Around an Outdoor AC Unit?


It can be very aggravating when your air conditioner doesn’t function properly, especially during the hot months. Many causes can result in your air conditioner not operating properly. It can be caused by simple issues such as a faulty thermostat and clogged filters. It can also be caused by more complex problems like compressor failure and refrigerant leaks. Make sure that you hire a certified HVAC expert to diagnose and resolve the issue.

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Townsend Energy offers affordable prices for our services because we understand the importance of a comfortable and energy-efficient home. Our maintenance services can help your home achieve enhanced indoor air quality, comfort, and energy efficiency. If you need to replace or repair your HVAC unit, our knowledgeable technicians can recommend the best option with your budget in mind. We guarantee all the work we do. 

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