AC not cooling? Find out why and how to fix your AC

HVAC Logo IconBy HVAC.comAugust 1, 2023
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When summer heat hits its peak, you need your home central air system to function properly. As outdoor temperatures rise, an AC not cooling your space can create a hot, uncomfortable feeling.

There are several possible reasons your air conditioner is working but not cooling your home. We’ll explore the most common AC problems, starting with the simplest fixes, then we’ll give you the top three ways to prevent spending a scorching summer afternoon in a home without AC.

Why is my air conditioner not cooling?

From a simple flip of the switch to replacing the AC compressor, these solutions will help get your HVAC system back up and running. When you discover your air conditioner not blowing cold air, give these remedies a try.

Check the thermostat setting

Start with the simplest solution first. Check your thermostat settings to ensure the device is on “cool” and “auto”. When the thermostat’s “auto” setting is used, the fan only operates when the unit is working to achieve your desired temperature.

The “on” thermostat setting means the fan will run continuously circulating the air in your home, but not necessarily cooling it. The noise created by the fan may lead you to believe the AC stopped blowing cold air, but a simple change in the settings should cool your space.

Clean or change the air filter

The air in your home carries a large amount of pollutants. Dirt, pet dander, pollen, and dust are captured by the air filter before the air is cooled and returned to your space.

When the filters become clogged, air flow decreases and you’ll notice the AC running but not cooling to your selected temperature. Monitor the cleanliness of your filters. Most suggest being cleaned or changed every 60 to 90 days, but if your filter needs to be replaced before then, make the change.

AC refrigerant leak

Similar to your vehicle, your home HVAC system relies on refrigerant, or coolant, to transfer the hot air out of your home and replace it with cool air. When the refrigerant is low or a leak has occurred, the AC will not adequately cool your space.

Other than the AC unit not cooling your home, a noticeable symptom of a refrigerant leak is a hissing or whistling sounds coming from your outdoor unit. This sound is indicative of air escaping through a pinhole or slice in the refrigerant line and may explain your steamy indoor temperature.

A line replacement and recharge of the unit are likely the needed fix. Recharging the unit is when an HVAC technician adds more refrigerant to the unit and pressurizes the chemical. The Environmental Protection Agency mandates that only a certified technician can recharge your home’s HVAC unit, so leave this repair to the pros.

Deteriorating ductwork

If the ductwork in your home is deteriorating due to age or damaged from an intrusion of animals (squirrels, raccoons, mice, etc.), you may be losing cool air. Misalignment or holes will allow cool air to escape the ducts before reaching your rooms, making it feel like the air conditioner is working but not cooling.

Other causes of ductwork damage may include improper installation or damage caused by a cable technician, home contractor, or other service provider. Inspect the ductwork in your attic or crawl space to determine if your hot home is created by an air leak.

Blocked condenser coils

The most common reason for a blocked condenser coil is dirt and dust. When particles become trapped inside the condenser’s small metal fins, the component can’t complete its job. The condenser is responsible for removing the heat energy from your home’s indoor air.

When the condenser is blocked or fails, the heat stays inside your home. It may sound like the air conditioner is working but it’s not blowing cool air. Use these simple steps to clean your AC condenser coils:

  1. Check for damage to the coils. If you notice any erosion or destruction, we recommend calling a local HVAC professional to inspect the severity of the damage.
  2. Remove obvious debris with a home AC coil brush.
  3. Use a fin comb to straighten bent coil fins. The brush will also remove hard-to-reach debris.
  4. Spray the coils with a garden hose. Remove the loose debris with water.
  5. Spray coil cleaner on the unit and allow it to sit for 5 to 10 minutes.
  6. Use a water hose to spray away the foam coil spray and debris. A sweeping motion with the hose will rinse away all remaining cleaner and dirt.

If the AC continues to run but not blow cold air, call an HVAC expert for help.

Frozen evaporator coil

The evaporator coil is located in the outdoor unit of your HVAC system. It’s responsible for absorbing the heat energy from the warm air inside your home. It then works with the condenser coil to cool the air and return it to your space.

If the evaporator coil becomes dirty or air flow is inadequate, the coil can freeze over. In this situation, you may notice a gradual change in the AC not cooling the house. You may also see an increase in your monthly energy bill.

In some cases, you can remove the front panel of your outdoor HVAC unit and see the coil encased in frost. It can take up to 24 hours to thaw the unit naturally, but calling an HVAC technician will help you identify the repair needed and get the system running properly.

Preventative measures for central AC not cooling

There are simple steps you can take to ensure your central air conditioning system runs smoothly and lasts its anticipated lifespan. Start inside your home with basic AC maintenance.

  • Change air filters regularly. Most filters need to be replaced every 60 to 90 days. However, if you live in a heavy pollen area or a couple of your family members have four legs and fur, check the filter more often and change it if it appears dirty.
  • Inspect your ductwork for damage. Head to your attic or crawl space to inspect your AC ductwork for damage or holes. This may be a preventative task you prefer an HVAC expert to handle. They may also recommend having the ducts cleaned to remove a build-up of dust and debris.
  • Install a smart thermostat. Boost the heating and cooling efficiency in your home with a programmable thermostat. Many thermostats have system-monitoring technology that will alert you to any potential malfunctions.
  • Keep the outdoor (condenser) unit clean. During routine yard work, remove leaves, sticks, and other debris that could damage or block the condenser coils.
  • Schedule routine AC maintenance. Avoid the situation of your AC not cooling your home with seasonal HVAC maintenance. A repair technician will inspect your system for damage, leaks, or wear and tear that should be addressed before the heating or cooling seasons begin.

Choosing the right HVAC company for your home is crucial to the proper upkeep and performance of your unit. Use our tips to research and hire the best heating and cooling company.

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