Noticing your AC blowing warm air? Now that's a reason to sweat. Don't panic. There are many different reasons why your AC is blowing warm air and sure, it can get kind of complicated.

But hold the phone. Before calling a professional, check out these 3 common causes that are simple to diagnose and easy to fix on your own.

Thermostat set to HEAT or fan set to ON

Yes, we're serious. Check your thermostat setting and make sure it's NOT set to "HEAT". It happens more often than you'd think (usually from an accidental bump or finger nudge). "ON" means the fan is always blowing air through your vents, even when your system isn't working to cool the air it blows. And, while that can help improve air quality if you have a whole-home air cleaner installed, it could also be the reason why you feel warm air (or at least air that isn't cooled) blowing through your vents.

DIY fix: Make sure your thermostat is set to "COOL". And use the "AUTO" setting if you don't have a whole-home air cleaner.

Outside unit clogged

Your home's AC system is made up of 2 main components— an outside unit and an inside unit. Both units work together to remove heat from your home. To do that, it needs unrestricted airflow to something called a "condenser coil", which is located in your outside unit. An outside unit clogged by dirt, leaves or debris can keep your AC from properly cooling your home's air.

DIY fix: You can prevent this problem by using a broom to sweep any visible debris away from your outside unit. Also make sure to trim bushes, weeds and tall grass that could restrict airflow.

Loss of power to outside unit

As we discussed earlier, your AC system is actually 2 parts that work together. If the outside unit loses power but the inside unit doesn't, it is possible that you could experience warm air coming out of your air vents. There are 2 places an outside AC unit can lose power:

  • At the circuit breaker. Check to see if the breaker for your outside unit got tripped.
  • An emergency shutoff switch. This is usually located on your home's exterior wall, right by the outside AC unit. Check to see it's in the "on" position.

DIY fix: Locate the breaker switch on your outside unit and flip the switch all the way OFF and then back ON.

Problems that need an AC repair professional

Here are a few more complicated causes that your AC is blowing warm air that will also require expert AC repair help.

  • Low freon/refrigerant Leak
  • Dirty evaporator coil
  • Return duct that is broken or disconnected

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