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5 Causes of a Central AC Blowing Warm Air

Sometimes your is AC blowing warm air instead of cold, refreshing air. It’s so frustrating, especially when it happens on a hot summer day. But how is that even possible?

Here are five possible answers.

Wrong Thermostat Setting

The most simple possible cause for a central air conditioner blowing hot or warm air is the thermostat setting. Maybe you forgot to switch it to “Cool” mode, and it is still in “Warm” mode. The fan should be in “Auto” mode. Don’t forget to check the temperature setting as well. There is also a chance that your thermostat sensor is not working properly.

Leaked Refrigerant

Your refrigerant may fail to cool down the air if it has even a small leak. A low amount of coolant liquid could also contribute to failure. It is not easy to directly check on your refrigerant because it is located inside the unit. However, there are some signs of leaked refrigerant such as:

  • Your outside unit is iced/frozen
  • There are hissing or bubbling noises coming from your AC unit
  • Your air conditioner blows hot air in the afternoon, but colder air at night

A refrigerant leak is not something you can fix yourself. You need to hire a licensed HVAC repairman to get the job done.

Disconnected or Leaky Air Ducts

Another common cause of a central air conditioner unit blowing out warm air is an air duct problem. If there is a crack or hole in the air ducts, cold air will leak out of it. In the end, only a small amount of cold air will make it into your room. Meanwhile, if one of your air duct joints is disconnected, the cold air won’t flow at all. Thus, only warmer air will make it to your room. Take a look at your ducts, if possible. If this is not possible, then you should get professional help.

Dirty Condenser

Do you perform regular maintenance on your home HVAC system? If not, then maybe your central air conditioner is blowing out hot air because your condenser is dirty. Without regular maintenance, dirt and debris build up around your condenser. As a result, your condenser won’t be able to remove the heat from your home. Therefore, it will flow back into your house.

Electrical Issue

Electrical problems with the outdoor unit of a central air conditioner may prevent it from cooling the air. Yet, your indoor unit will still do its job of blowing out whatever air it has. Thus, it will end up blowing out warmer air that the outdoor unit failed to cool. Try resetting your circuit breaker or fuse. If the problem persists, you need to get professional help from a licensed electrician.

Nobody wants hot air blown out of their central AC unit. But at least now you know what to check for if this happens to you.

For more information, read: Does Your AC Unit Blow Colder Air on Hot Days?


ecm-air-conditioning-in-60-minutes-or-less-mascotECM Air Conditioning, with its headquarters located in Boynton Beach, FL, provides air conditioning services within Palm Beach County, Broward County, Martin County, and St. Lucie County. If you’re having issues with your HVAC system, we’re on-call and ready to assist you with your air conditioning needs. So if you’re in need of AC service, don’t hesitate to contact us today to schedule an air conditioning service call diagnostic! Our AC service experts will diagnose any issues that may be occurring with your HVAC system and help to repair your AC issue on the spot. If you’re in need of a new air conditioner we offer a Free AC Estimate as well as Free Second Opinion on a new air conditioner unit.

Best of all because ECM is the largest AC company in South Florida our local warehouse facility that is 69,000 SQFT houses over $1 million in inventory and fully stocks our 127 vehicles on the road, making us one of the very few AC service companies capable of repairing most issues right on the spot. That means no waiting and no downtime without air conditioning for you & your family in the blistering Florida heat! 

Call us at 561-295-1763 or contact our AC service team online by clicking here.

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