Central AC Not Blowing Cold Air? 3 Possible Causes

Posted on: 10 June 2021

Does it feel like the air from your air conditioner is never quite cool enough to make your home comfortable? Many homeowners have experienced this problem. Lukewarm air from your air conditioner could be caused by a variety of different HVAC issues. Here are three things that may be keeping your central air conditioner from blowing cold air.

1. Incorrect Thermostat Settings

A seemingly minor change in your thermostat settings can completely alter the way your HVAC system behaves. If your AC isn't cooling, start simply by checking the thermostat. Make sure the temperature setting is set to "cool" rather than "heat."

The next setting you should check is the fan control. If this control is set to "on" instead of "auto," the blower fan will run continuously even if the furnace and air conditioner aren't running. It's easy to forget about this setting and run your HVAC system in fan-only mode when you intend to use the AC or furnace.

If you have a smart thermostat, you will want to find out if it has a scheduling feature and become familiar with it. This way, you won't be surprised by any default settings that could cause your HVAC system to run at unexpected times.

You'll save money and be ahead of the curve if you take advantage of the scheduling feature, too. In a study by researchers from the University of California, 90% of respondents reported that they don't use schedule their smart thermostats, despite the fact that residential heating and cooling accounts for 9% of the total energy use in the U.S.!

2. Obstructions Around Condenser

The evaporator coils in your central air conditioner cool your home by circulating refrigerant and absorbing heat from the air. The heated refrigerant is then delivered to the outdoor condenser where the heat is dispelled outside. 

It's important to leave enough space around the condenser to promote airflow and prevent it from overheating due to trapped heat. An overheating condenser will no longer be able to condense and cool the refrigerant in your system once its internal temperature nears the temperature of the outside air. Consequentially, the evaporator coils won't be able to absorb heat and the air from your vents won't be cold.

Your condenser can be blocked by tall grass, bushes, and vines, as well as dirt lodged in the fins on the outside of the unit. Make a habit of trimming vegetation around your condenser, and spray it down occasionally with a garden hose to keep the coils and casing clean.

3. Dust on Evaporator Coils

As mentioned above, your evaporator coils absorb heat from the surrounding air. However, evaporator coils that are coated with dust and dirt will not be able to transfer heat effectively. Furthermore, grime on your evaporator coils will eventually drip into the drain pan beneath the coils. Over time, this can cause a clog in the condensate drain line that will need to be removed before you can run your HVAC system.

You can choose to hire an HVAC technician to clean your evaporator coils, or you may attempt the project on your own. To clean the coil yourself, you will need a chemical coil cleaner and a paintbrush or nylon brush. For most products, you simply allow the foam to rest on the coils for a few minutes and then use the brush to remove any remaining debris.

Sometimes, a few simple troubleshooting steps may be all you need to return your central air conditioner to working order. If your AC still isn't providing the cold air your home needs, it's time to call a residential HVAC technician for a professional inspection.


update that old heating system

How long have you been putting off replacing your heating system in your home? Do you worry that the cost of the new system will cost you too much? Have you thought about how much you are losing by not replacing that old furnace? This blog will help you understand how making an investment on a new heating system for your home can actually save you a lot more over the next ten years than you spend on the system and the installation work. Hopefully, by the time you are done reading, you will know what you have to do and why you shouldn't put it off any longer.

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