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Here’s Why Your Air Conditioner Is Blowing Warm Air And How To Fix It

Here's Why Your Air Conditioner Is Blowing Warm Air And How To Fix It

Summer is here in full force. While pool parties and barbecues are fun ways to spend the summer, we all rely on the shelter of our homes to provide a welcome break from the heat.

This is when our air conditioners are most needed. This is also HVAC technicians’ busiest season. Every day during the summer, we receive calls about air conditioners that are blowing warm air. Fortunately, this is a common HVAC issue that may occasionally be fixed by the homeowner.

“Why is my air conditioner blowing warm air?” you might be wondering.

If Your Air Conditioner Is Blowing Warm Air, What Should You Do?


Here's Why Your Air Conditioner Is Blowing Warm Air And How To Fix It

The thermostat is the first thing you should examine, which may seem obvious. If your air conditioner is blowing hot air, it’s possible that the thermostat was accidentally set to “heat,” which is a straightforward fix. Simply set the thermostat to “cool” and wait for the air conditioner to start blowing cool air again.

Double-check that the batteries are fully charged and that the temperature is not too high. Remember that the “auto” setting just heats or cools the air with the fan. Even if the air conditioner or heater is switched off, the “on” setting indicates the fan will run constantly to circulate the air. We recommend using “auto” most of the time and just switching to “on” when absolutely essential.

THE SOLUTION: Make sure the thermostat is set to “cool” and at the right temperature. Replace the batteries if necessary. We recommend setting the thermostat to roughly 78 degrees Fahrenheit during the cooling season and 7-10 degrees higher while away from home. You can save 10% on your annual heating and cooling bills if the setback time is 8 hours long (U.S. Dept. of Energy).

Is it time to replace your thermostat? Find out how to select the best thermostat for your home.

Circuit Breaker

Here's Why Your Air Conditioner Is Blowing Warm Air And How To Fix It

To confirm that the HVAC system has electricity, inspect the electrical panel after checking the thermostat batteries and settings. HVAC systems use a lot of energy to run. As a safety measure, the circuit breaker may automatically shut off electricity when there is an excessive level of power demand.

THE SOLUTION: Inspect your electrical panel for a tripped breaker or blown fuse. To restore electricity to the unit, turn the breaker completely off (in the opposite direction as all other breakers) and then back on. You’ll have to repair a blown fuse. This is also a good time to name all of your circuits so you can readily locate them if one is overloaded again.

You should contact a professional HVAC specialist or electrician if your breaker keeps tripping for no apparent reason.

Coils for the Air Filter and Evaporator

Although air filters have little effect on air temperature, a dirty air filter can lead to a dirty evaporator coil. If the evaporator coil becomes clogged with dust and debris, there may not be enough free airflow to allow for efficient cooling. Evaporator coils might freeze due to debris buildup from a dirty air filter. Although “frozen” may imply “cold,” the frozen coils actually hinder the flow of frigid air, causing warm air to flow from the operating engine instead.

The owner should change the air filter every 30-60 days, depending on the climate, filter type, and household. Setting a monthly reminder to check the status of your air filter at the beginning of each month is recommended. When you hold the filter up to the light, it barely lets any light through, it needs to be replaced.

THE SOLUTION: If your evaporator coil is frozen, turn off the system and replace the air filter. Wait until the freezer has thawed before turning it back on. If the coils freeze up again, turn off the unit and contact a professional HVAC expert for assistance. If you have a refrigerant leak or a compressor problem, you will need professional help.

Coils for Condenser (Outdoor Unit)

It’s time to evaluate the outside unit now that you’ve checked the thermostat, breaker box, air filter, and indoor coils. Outdoor evaporator coils, like indoor evaporator coils, require open airflow. As a result, it’s best to have a 2-foot distance around the outdoor condenser unit at all times.

THE SOLUTION: Turn off the unit at the source if your outside unit is clogged. Then, using gloved hands, remove the larger things and rinse away the smaller material with your garden hose. Learn how to clean your outside condenser unit step by step.

At the start of each cooling season, remember to schedule a professional air conditioning tune-up and cleaning. Check to see if your HVAC company’s regular tune-up includes comprehensive indoor and exterior coil cleanings. In addition to professional cleanings, it’s a good idea to inspect and clean the exterior unit on a regular basis.


Low refrigerant is one of the most common causes of a broken air conditioner. You could have undercharged or overcharged refrigerant if you have a worn service valve, loose joints, or faulty assembly.

THE SOLUTION: Refrigerant (also known as coolant) is extremely hazardous. You should never try to address refrigerant problems yourself unless you are a skilled specialist. Schedule annual air conditioning tune-ups before the cooling season begins to avoid refrigerant leaks in the first place. Act fast if your air conditioner is spewing heated air, making hissing/gurgling noises, or has ice on the refrigerant line. The sooner you react to refrigerant that is under or overcharged, the better. As quickly as possible, contact a local HVAC firm.

IMPORTANT NOTE: Do not trust a professional who simply adds refrigerant to your system. Because refrigerant is used in a closed loop system, a lack of refrigerant indicates a leak someplace. Before adding any refrigerant, your HVAC professional should fix the leak. If you don’t patch the leak, you’re only postponing the problem rather than solving it.

Additional Air Conditioning Advice for Summer:

Here's Why Your Air Conditioner Is Blowing Warm Air And How To Fix It
  • When you’re at home, set the thermostat to 78 degrees, and raise it to 7-10 degrees when you’re away.
  • To feel 4° cooler, use your ceiling fan.
  • Proper ventilation can help prevent moisture concerns.
  • Sign up for a home maintenance plan so you don’t forget about your annual tune-ups.
  • Set a 30-day reminder to check your air filter.
  • When using the air conditioner, keep all doors and windows shut.
  • Regularly clean and dust your home.
Here's Why Your Air Conditioner Is Blowing Warm Air And How To Fix It

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