There is nothing worse than your AC failing to cool you down in a heatwave. Is your AC not blowing cold air? This AC failure can be traced back to a few different causes, some easier to fix than others. Read on below!

1. Your thermostat is not set correctly or is faulty.


Before a deep investigation into your central AC unit, you should first look at your thermostat. If your home is feeling warmer than normal even though your AC is on, it could be that your thermostat is either set incorrectly, has low batteries, or has a wiring issue.

Young woman controlling room temperature with a smart thermostat at home.

What To Do

Make sure your thermostat is set to cool (not heat or fan only). Make sure that the temperature settings have not changed from what you programmed. Make sure the batteries are in working condition. If all these things look correct, your AC problem may have another cause.

Dirty furnace filter.

2. Your filter is dirty, blocking the cold airflow into your home.


Believe it or not, a dirty air filter can cause the air from your AC unit to not feel as cool as it should. As you can probably guess, the buildup of lint, dust, hair, and other particles prevents proper airflow of the cool air into your home! A dirty filter can even cause your AC to shut down completely if it’s not getting enough air, leaving your home feeling more hot and humid than ever. Besides the discomfort that a dirty filter can cause, neglecting to change it causes extreme wear to your AC unit and its components.

Symptoms you will notice when you have a dirty filter include:

  • Filter color. Take out your furnace filter. If it’s grayish (instead of its regular white color), it is covered in dust and hair and needs to be replaced.
  • Low airflow. If you hardly feel air coming through your vents, it’s because the filter is clogged and restricting airflow.
  • Bodily reactions. You may find more severe allergy symptoms, congestion, and headaches caused by the dust and other particles permeating the air.
  • Higher energy bills. A clogged filter makes your HVAC work harder and use more energy to deliver conditioned air to the home.
  • Potential breakdown of HVAC. The more your HVAC system has to exert unnecessary energy, the more likely you’ll see it overheat and stop running, or wearing out parts extremely quickly.

Why does my furnace filter get dirty so fast? You’ll notice that you cycle through filters faster when you:

  • Have indoor pets.
  • Burn a lot of candles.
  • Use your HVAC more often due to weather that’s hotter or colder than usual.
  • Have a lot of dust in your home, on surfaces, or in carpets.

What To Do

Thankfully, a dirty filter is an easy fix. Simply purchase a new one, either from a store or a local HVAC company, that matches the size of the existing filter. Make sure to install it correctly, with the arrows pointing toward the furnace. If you’re unsure of the filter replacement process, get help from an HVAC professional. Remember, your filter needs regular changing, with the timeline depending on the size of your filter and the size of your home. If it’s not regularly replaced, it can contribute to both AC and furnace problems.

3. Your AC unit has a leak and is low on freon.


The refrigerant, called freon, inside your central air conditioning unit is what cools and conditions the air before it enters your home. When your freon is leaking out, you will notice over time that the air blowing in from your central air conditioning unit is getting significantly warmer and warmer than it should be. This may be a long gradual process as the unit loses more and more refrigerant.

Here’s the problem: the refrigeration system inside your AC unit is closed, meaning that the refrigerant should not be escaping in any way during normal operation. Your unit is not designed to need refills. Having to fill up on leaking refrigerant (freon) indicates a leak in the system, most often in the evaporator coil. And unfortunately, the freon will leak regardless of whether your AC is off or on and no matter how often you’re using it.

Signs or symptoms of a freon leak include:

  • Warm air blowing from vents. Without enough refrigerant, the air is unable to be adequately cooled for your home.
  • Frozen Evaporator Coils or Condensate Lines. Without an adequate amount of freon, your system can’t absorb heat, and the condensation on the coils and lines freezes.
  • Higher Energy Bills. With less freon, your AC system works overtime to try to reach the set temperature on your thermostat, often costing you on utility bills.
  • Sounds and Smells. A refrigerant leak may manifest itself in hissing noises or a range of chemical smells in and around the unit.

What To Do

If the leak is minor, you may choose to get your freon refilled. In this case, you should also get a leak check and repair to prevent your refilled refrigerant from leaking out again.


How to Add Freon To Your Home’s AC

Recharging your AC with freon is not something you should DIY, considering the cost of both the refrigerant and the unit you are dealing with. Besides, EPA regulations require that those who handle refrigerants be licensed to do so.

If you suspect your AC not blowing cold air due to a lack of refrigerant, you should schedule service with an HVAC technician who is licensed and experienced to handle the issue. Our yearly AC tune-ups include a refrigerant test and are designed to catch these problems before they become larger issues.


Schedule Your Service Today.

Consider A New AC Unit.

When excessive freon leaks become a problem, you should consider purchasing a new air conditioning unit as soon as possible. Why? Refilling refrigerant just to make it through another heating season (and having it all leak out) is quite literally throwing your money down the drain. Plus, with older AC units, the type of freon you need may not even be available or is very expensive. You should know that many HVAC companies will not warranty their work on freon refills when there is a leak present on an old AC unit because the leak will reoccur with no fault of theirs. It is a very real possibility that the new freon could even leak out the next day, leaving the homeowner out hundreds of dollars, depending on how many pounds of refrigerant was put in.

Air conditioning units outside a home.

4. There are problems within your AC unit or outdoor condenser.


There are two common possibilities within your unit that may be the cause of your AC not blowing cold air. They are dirty condenser coils or frozen evaporator coils.

The condenser coils become dirty over time in the process of cooling the refrigerant. This dirt comes from the outdoor air and eventually builds up on the coils. This buildup can render your unit unable to produce cool air, even though the unit itself is still running.

The evaporator coils inside your unit and the condenser lines may freeze when there is a lack of refrigerant. Without an adequate amount of freon, your system can’t absorb heat, and the condensation on the coils freezes. Frozen coils may also be due to lack of airflow, part malfunction, or a dirty filter preventing them from getting the heat they need from the air.

What To Do

If your condenser coils are dirty: Your condenser coils need to be cleaned regularly to keep your AC running efficiently. The coil cleaning process involves inspection, straightening of any bent coils, removal of large debris, and using a coil cleaner to remove heavy dirt, dust, and grime. If you’re not the DIY type, Air Conditioner Tune-Ups include this service! Getting a yearly tune-up is one way to always make sure the coils stay clean and your AC is ready for a heatwave.

If your evaporator coil is frozen: When the cause behind your frozen evaporator coil isn’t immediately apparent, you should consult an HVAC professional. (In the meantime, turn off the AC unit and let the coil thaw! Without any assistance from another source of heat, the thawing process could take up to 24 hours.) A professional will be able to tell you whether the refrigerant is low, and from there whether it is wiser to recharge with freon or to replace the unit.

Blakeslee & Son: Serving West Michigan for over 70 years.

Is your AC not blowing cold air? Don’t wait til the heat becomes unbearable—call the experts and get on the schedule today! Blakeslee & Son does thermostat repair, filter replacement, AC Tune-ups, refrigerant refills, and new AC installation in Rockford, Grand Rapids, and the surrounding areas. Now offering emergency HVAC service from 8 AM to 8 PM every day.


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