Possible Reasons for Why Your AC is Blowing Warm Air

It can be rather frustrating to feel warm instead of cold air blowing out of your registers. There are a few different reasons why your air conditioner isn’t producing cool air. You can do something about resolving some of these problems yourself, while other ones need to be repaired by an HVAC technician.

Your Thermostat Is the Problem

If your AC is blowing warm air, the first thing you should check is your thermostat. Look at its settings and make sure it isn’t set to “heat.” The thermostat settings may have not been changed after winter. Or it could have been accidentally bumped, or your child could have been exploring it. Make sure your thermostat is set to “cool” for the AC to come on.

Make sure the fan setting on your thermostat isn’t set to “on.” This setting may sound appropriate, but it isn’t. When the fan setting is set to “on,” the fan will always blow whether your AC is on or not. Whenever the AC is off, you’ll feel warm air blowing out of the vents. Set the fan setting to “auto” so the blower only operates when the AC is on.

Clogged Air Filters

The air filters in your HVAC system trap dust, dirt, pollen, pet hair, and other pollutants. If the air filters aren’t regularly changed, they can become clogged with debris. Once they’re clogged, they will cut off the flow of air. The result is your AC blowing warm air into your home.

You should change the air filters every one to three months. You need to change them more often if you have a large home, pets, and family members with allergies. You will also need to change them more often if you use your AC a lot.

Closed or Blocked Returns or Registers

Returns and registers need to be open and unblocked for proper airflow through your house. Make sure all of them are open and that they don’t have something blocking them like a curtain, furniture, or a rug.

Leaky or Disconnected Ducts

The reason you’re feeling warm air from your registers could be because of a problem with your ductwork. If a return duct has holes in it or has become disconnected, it prevents air from getting back to your AC unit. If there’s an issue with the supply ducts, cooled air will get blown into your crawl space, attic, or walls.

Inspect any ducts you can see for holes or if they’re disconnected. You’ll need the help of a technician to find any problems in hidden ducts. It is possible they were damaged by rodents or birds or during a construction project.

Dirty Evaporator Coils

Your AC system’s evaporator coils need to be clean for them to do their job. The evaporator coils absorb hot air from your home and cool it using a refrigerant. If they are dirty, they have a harder time absorbing hot air. When this happens, your AC system will start blowing warm instead of cold air.

You can help keep your evaporator coils clean by scheduling AC maintenance every spring. As part of this service, a technician will clean the evaporator coils and make sure they are in good operating condition.

Trusted Heating & Cooling offers AC maintenance to families in Austin, and surrounding communities. We have been proudly helping people since 2013.

Dirty Condenser Coils

Dirty condenser coils can also cause warm air to blow. These are in the outdoor AC unit and are subject to the elements. Their job is to remove heat and blow it outside your home. As they’re outside, they can get covered in grass, leaves, dirt, and grime. This reduces heat transfer, so warm air blows.

You should gently spray your outdoor AC unit with a garden hose at least once a summer or when you see it is dirty. Shut off the power before doing this. Also clear the surrounding area by removing weeds, branches, and other debris. A technician will clean the interior of the outdoor unit during AC maintenance.

Fan Issues

The fan in your HVAC system may be the culprit for why your AC is blowing warm air. It could have worn belts or a malfunctioning motor. It also may not have been lubricated, or it’s collected dust and dirt. This results in a lack of airflow and warm air blowing instead of the cool air you were expecting.

When you schedule AC maintenance, the technician will lubricate parts and check the belts in your fan. This will help your AC system blow cool air all summer long.

Refrigerant Leak

Your AC system must have sufficient refrigerant for it to blow cool air. Refrigerant is used to move warm air from your home, so it can be blown to the outdoors. When the refrigerant is low, you’ll feel warm air coming from the registers. You can see if there’s a refrigerant problem by looking at the evaporator coils. If they are frozen over, you probably have a refrigerant problem.

The refrigerant flows through a closed system. When it’s low, that means there’s a leak somewhere. You need to have a technician recharge the refrigerant. They will inspect your AC system to find the leak and then fix it.

Be aware if you have an old AC system, it may use a discontinued refrigerant known as R22. You may not be able to charge the refrigerant in your system, or it will be very expensive to do so. You may need a new AC system to get cool air blowing once again in your home.

Clogged Condensate Drain Line

Your indoor AC unit pulls humidity from your home. The moisture that it collects is supposed to drop into a pan and then go through a condensate drain line from which it is discharged outside your home. This line can become blocked by dust, dirt, mold, mildew, and other debris. When that happens, water can back up which can damage the AC system. It can even cause water damage to other areas of your home.

If you see water around your furnace, it’s likely being caused by a clog in your condensate drain line. You can pour a one-quarter cup of distilled white vinegar into it to clear the clog. If that doesn’t work, use a wet-dry vac. To prevent this problem, pour vinegar into it every month that you’re using your AC system.

Failing AC System

The cause of warm air blowing from your vents may be that your AC system is old, worn out, and needs to be replaced. Most AC systems last 15 to 20 years, with poorly maintained ones lasting an average of 10 years. You can help it last longer by scheduling annual AC maintenance.

Trusted Heating & Cooling is a family-owned and operated company that performs repairs, replacements, and maintenance of heaters and air conditioners. We also work on air conditioners, heat pumps, furnaces, geothermal systems, and packaged systems. Our company also does ductwork. Find out how we can help you by calling us today.

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