Aug 13, 2018

Why Is My AC Unit Blowing Warm Air?

You turn on your air conditioner and stick your face in front of it, anticipating that icy cool blast of refreshing air. Instead, you feel a stream of warm air like a giant’s fetid breath on your face. Is anything worse?

There are a few reasons why your air conditioning unit may not be working properly. Here, we answer your most important questions about malfunctioning air conditioning units. Why does my AC blow warm air? And how can I fix my air conditioning unit?

Why Does My AC Blow Warm Air?

To understand why your air conditioner is blowing warm air, you need to know how the air conditioning unit functions. (See a term you don’t know? Look it up in our HVAC glossary!)

An air conditioner uses refrigerant to cool the warm air in your home by converting it from a liquid to a gas. The refrigerant absorbs the heat of the air as it changes. Then, a compressor pressurizes the gas, creating more heat. The heat is pushed outdoors via the condenser coils, and the gas changes back to a liquid. Refrigerant is at the heart of the air conditioning process. A problem with the refrigerant could be the reason why your AC is blowing warm air.


Refrigerant cools the air in your AC unit. If it’s low, air will still circulate through your unit but it won’t cool as it converts from a gas to a liquid. It will simply stay the same temperature as it circulates through the system. You might need a refill of your refrigerant, or it might be leaking somewhere.


If you aren’t keeping the coils clean through AC unit maintenance or you aren’t changing the air filter regularly, the coils can freeze. The dirt and debris prevents airflow over the evaporator so the cool air can’t escape. Unfreezing or deicing your AC unit isn’t a DIY job. Only qualified experts should handle refrigerant. If your air conditioning unit is freezing up, it could be causing it to blow warm air. Call the professionals to diagnose and fix your problem.


If your compressor and condenser (located on your outside unit) don’t have power, the air conditioner blows warm air. A blown fuse or tripped circuit breaker kills power to the HVAC system. It could also occur if the emergency shutoff switch is hit accidentally. If your outside unit isn’t turned on, you’ll end up with warm air blowing through the unit.


File this one under #HVACFails.

You’ve probably checked this, but is your thermostat set correctly? If you’re in heating mode rather than cooling, you’re going to get warm air. Make sure that your thermostat is in the proper mode and that the temperature is correct. While you might feel silly, this is one of the easiest problems to fix!

Check Out 5 Reasons Your AC Isn’t Working Here

How Do I Fix My Air Conditioner?

The fix, of course, depends on the problem. If you’ve checked that your thermostat is properly set and that your unit has power, the next step is to clean the unit. Change the air filter. Brush any debris away from the condenser coils and hose them down. Your outside unit needs at least two feet of cleared space around it.

If your AC unit is blowing warm air after these DIY fixes, it’s time to call in the experts. You may be low on refrigerant or you might have a refrigerant leak. The condenser could be failing. Your compressor may not be working properly. An air conditioning unit is a complex system with several parts. If you need AC repair in Raleigh or Wilmington, Newcomb and Company technician can quickly figure out why your AC unit is blowing warm air. We’ll fix the problem so you can get back to enjoying your cool, comfortable home.

Need help? Call now.