Troubleshooting Tips When Your AC Is Blowing Warm Air

Troubleshooting Tips for When Your AC is Blowing Warm Air

When summer arrives, temperatures will start to rise and lead to uncomfortable homes and workplaces. Having a well-maintained AC unit installed enables you to keep temperatures low, giving you the comfort you deserve throughout the season. But when you wake up sweating profusely in bed, it suggests a malfunctioning cooling system. And one of the most common problems is when your AC is blowing warm air. Several reasons can make your AC break down and start blowing warm air. Therefore, it is crucial to learn the common causes of your AC blowing warm air and troubleshooting tips. That said, read on to learn more about troubleshooting faulty air conditioners before calling an HVAC technician to repair your air conditioner.


An AC unit blowing warm air is a conventional problem most homeowners face during summer. It is no fun feeling as you tend to sweat more and become unproductive due to the scorching sun and increased air humidity. So, what makes your AC blow warm air during summer? Here is why;

  • Dirty filter: A dirty filter limits airflow through the system, eventually straining your AC and making it blow warm air.
  • Clogged/dirty outside AC unit: Both the outdoor and indoor AC units work together to supply cool air during summer. But once the outdoor unit gets clogged with dirt and debris, it makes it hard to remove heat from your home or office.
  • Thermostat issues: At times, the problem may revolve around your thermostat setting, which may be set to supply warm air rather than cool air during summer.
  • Refrigerant leak: Because refrigerant is responsible for absorbing heat, any leaks or low levels would mean minimal or no cold air entering your home, resulting in a warm air supply.
  • Frozen evaporator coils: Like the refrigerant, the evaporator coil plays a critical role in cooling the air entering your home, but your AC will blow warm air once the evaporator coil is frozen.


When your AC starts to blow warm air, it is usually inconveniencing and uncomfortable at the same time. Because there is always a reason for the breakdown, troubleshooting your cooling system comes in handy. Here are practical troubleshooting tips for your malfunctioning AC.


checking the thermostatModern thermostats have various settings. In this case, AUTO function and ON settings for the fan. The AUTO function means the fan will blow cool air whenever temperatures in the room start to climb. On the other hand, the ON setting means the fan will always blow cool air unless it is turned OFF. Check your thermostat to ensure settings are on AUTO and the COOL setting is selected.


If you have dusty air filters, you can either clean or replace them entirely. However, cleaning may not be an option if your filters are filthy. Changing them can be the best solution to guarantee other components within your AC remain clean. If your thermostat checks out and still experiences a warm air supply problem, the problem might be in your system’s air filters. Here is how to go about it:

  • Turn your AC off
  • Remove the filters
  • Inspect them for any dirt and debris buildup


Your cooling system’s refrigerant is a crucial element that facilitates heat transfer. It also allows the entire unit to function correctly and blow cool air during summer. Any leaks can be adverse and compromise your unit’s performance, including adequate cooling. Testing refrigerant leaks is crucial to help you understand if it is enough to cool the air. While there are three common ways to test refrigerant leaks, the simplest form is the ‘soap bubble’ test. Here is how it works:

  • Switch off your AC system
  • Make a soap solution and pour it into a spray bottle container
  • Make sure the test area is free against the wind
  • Clean the area using a dry cloth
  • Spray the solution over the surface and watch for soap bubbles.

If soap bubbles don’t form, it is likely your AC has a refrigerant leak. However, you may need to contact an HVAC technician to assess your system and perform a test using specialized tools. A technician can double-check to ensure your AC has adequate levels of refrigerant to facilitate the cooling process.


Your outdoor AC unit might be the actual cause of your system blowing warm air during summer. Primarily, the condensing unit collects dirt and debris that may obstruct airflow, making the AC inefficient and likely to blow warm air. Homeowners with central AC units should examine their condensers for dirt, plant life, or other debris. For dirty condenser units, scrubbing them clean with foaming coil cleaner and a garden hose can help remove dirt. If it is clogged with plant life or overgrown branches and leaves, cut them down or remove any leaves, including other debris preventing airflow into your system. If you have a window unit, remove it and take it outside for a cleaning job. While outside, remove it from the mounting frame and case, and with compressed air, household cleaner, and a soft-bristle brush, remove debris and other unwanted materials.


The problem of your AC blowing warm air could be a result of a failing compressor. This is a vital component of your cooling system responsible for the heat transfer process essential for cooling. When the compressor malfunctions, calling for an HVAC technician is your best chance to get your AC repair job handled by an expert. Thus, listen for any of these noises;

  • “Chattering” or “ticking” noises: These noises often suggest that the compressor is having difficulties turning on and cooling the air.
  • Rattling/clicking/rumbling noises: When the compressor motor fails, it could start moving within your unit and cause more problems, causing loud and uncommon noises.

If you hear unusual or strange noises from your AC unit, it could indicate a failing compressor. Calling a technician could help confirm your concerns and recommend the right step to fix the issue.


Your cooling system’s evaporator coils extract heat from the air and initiate the cooling process. But with condensation being the byproduct, moisture may collect on the coils and freeze. Once condenser coils become frozen, your air conditioner will start blowing warm air. Frozen evaporator coils can emerge from several causes: system damage, refrigerant leaks, or poor airflow. Checking your air conditioner for signs of frozen evaporator coils can help fix the issue. Here is how to troubleshoot frozen evaporator coils:

  • Shut down your air conditioning system
  • Open the access door to the system’s interior components
  • Evaluate the evaporator coil for any signs of frost or ice buildup

If you notice frost or ice on the coils, the best solution is always to give the coils time to thaw. Leaving it for 24 hours can help, but you can also use a heat gun or hair dryer to thaw coils much faster. Because it is a delicate process to pass heat over the ice, hiring an HVAC technician can help hasten the process and avoid further damages to your AC unit.


Because your cooling system is a delicate and complex appliance, finding the source of the problem when your AC blows warm air can be a daunting task. Here at Aquarius Home Services, we can perform a complete troubleshooting job on your system, analyze it, and fix the problem to make sure it is functioning correctly. Contact us and let us get you back to enjoying cool, clean, air-conditioned air!

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