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5 Reasons Your AC Might Blow Warm Air

By Newcomb and Company July 22, 2021


The last thing you need in the middle of the summer is more heat. For some homeowners, this becomes a reality when their AC starts blowing warm air. Sometimes an AC blowing warm air is a quick fix, but it can often require expert AC troubleshooting and repairs to get it working at peak performance again. By knowing some of the main reasons why your AC stopped blowing cold air, you can determine if you need professional service and take action on the issue faster.

Check out the top five reasons your AC might blow warm air below:

1. Thermostat Errors

Before you contact someone for AC repairs, one of the simplest AC troubleshooting steps you can take is to check your thermostat. Thermostat troubles or misconfigurations can commonly cause warm airflow from your air conditioner. Here is a look at some of the most common thermostat issues you might be experiencing:

  • Thermostat settings: While it might seem obvious, sometimes a thermostat is set to heat rather than cool by accident. Of course, when a thermostat is on its heating setting, it will blow warm air into your home. If you see that your thermostat is set to heat, simply switch it to cool and check if it starts blowing cold air.
  • Thermostat troubles: Another common issue is that your thermostat’s batteries have died. If this is the case, a new set of batteries should fix the issue. Homeowners also should see if they are due for a thermostat calibration or a thermostat update.
  • Fan settings for thermostats: You can often address warm airflow by switching your thermostat fan from its “on” option to its “auto” function. If your AC fan is turned on, the fan will continuously run—even when your AC is on standby. When your air conditioner is not cooling but your fan is still circulating air, your vents may begin to produce warm air. In contrast, a thermostat set to auto will only run the fan when it has cool air to circulate.

2. Frozen Evaporator Coils

If your AC is blowing warm air into your home, the issue could be frozen evaporator coils. Since these coils are designed to capture heat like a sponge via their refrigerant, a frozen coil can cause the refrigerant to ice over and no longer soak up the heat. A frozen evaporator coil is often caused by poor airflow that makes them get too cold.

When ice builds up and the refrigerant fails to capture warm air, your AC will start to blow warm air into your home. At times, frozen coils can even cause your system to stop working entirely. Frozen coils often come from dirty air filters, as a dirty filter will inhibit proper airflow through your HVAC system.

Though a dirty filter is often an easy fix, you’ll still need to contact a specialist to handle the frozen coils. Since frozen coils are prone to damage if they’re handled improperly, it’s crucial you have a professional conduct an inspection and repair. Once you hire the specialist, they’ll review your system to see if frozen coils are the culprit and then take action, cleaning, repairing, or replacing your coils as needed.

3. Refrigerant Leaks

A refrigerant leak is another major reason your HVAC system could be blowing warm air into your home. Due to refrigerant’s role in absorbing your home’s heat, a leak can cause your AC to start blowing warm air. If the AC doesn’t have enough refrigerant in it, it will struggle to cool the air as it passes through your system.

Leaks are the most common source of low refrigerant, so it’s crucial you hire someone to see if it’s leaking. A professional will check for signs of leakage, such as cracks and frozen outdoor and indoor AC units. Once they find where the leak is occurring, they’ll seal any cracks and refill the AC’s refrigerant back to optimal levels.

4. Dirty Filters

When an AC’s air filters start to get dirty, the AC will struggle to blow air throughout its system and your home. Since the AC will have a harder time moving air, it can start to work overtime, raising the chances it breaks down and starts to blow warm air into your home.

A dirty filter is a quick fix most homeowners can perform on their own. You only have to replace the dirty filter with a clean one and wait to see if the AC starts to blow cool air again.

When should you change your air filters? Most air filters should be replaced every 30 to 60 days, with this time frame ranging based on the home, climate, filter type, and a wide variety of other factors. No matter where you’re located, you can safeguard yourself against dirty filters by checking them every month. A good way to tell if your filter is too dirty is to hold it up to a light. If you see that the filter only lets a small amount of light through it, it’s time to replace it.

5. Outdated Units

When an air conditioning system is properly maintained, it usually lasts around 10 to 15 years. If your AC unit has started to blow warm air and it’s passed the 10-year mark, you may need to replace the unit. Besides blowing warm air, an outdated unit may also start to raise your energy bills, as it won’t be able to cool your home efficiently.

If you can’t identify any reason why your AC unit would be blowing warm air into your home, it’s time to call a professional. An HVAC technician will come to your home and inspect your system to see if it needs a full replacement. They might find you only need a repair, but they may discover your AC unit is on its last legs. A great HVAC company will take your home’s needs into account and recommend a cost-effective, efficient AC unit.

Turn to Newcomb and Company for AC Repair Services in Raleigh

If you live in Raleigh, Wilmington, or the surrounding areas, choose Newcomb and Company for your AC replacement and repair needs. When you hire us, our HVAC professionals will take the time to understand your AC system and its needs to give you the best service possible.

When a repair doesn’t cut it, we can even provide you with AC installation and replacement to ensure you receive the best HVAC system for your home. You can also sign up for our comfort contracts to help prevent AC problems from occurring in the first place.

You can review our AC repair services here today. If you have any questions or want a free estimate, please feel free to contact us.