Why Is My AC Blowing Hot Air?

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Updated February 3, 2023

There’s hardly a more uncomfortable summertime irony than an air conditioner blowing warm air. Unfortunately, this problem isn’t all that uncommon and can happen to even the best air conditioners. So, if you’re asking yourself, “Why is my air conditioner blowing hot air?” below, we’ll explain the common causes and what to do when it happens.


  • Any AC may blow hot air if the airflow is restricted or not cooled.
  • The first place to check whenever an AC unit is blowing hot air is the thermostat settings.
  • Check the air filter and refrigerant levels while ensuring nothing is blocking the AC return vents.

Why Would an Air Conditioner Blow Hot Air?

It’s important to note that there is no singular cause for an AC blowing warm or hot air. Instead, there are a few common causes that owners should first check to understand why it’s happening. Sometimes, warm air indicates a minor fix, like a dirty air filter. or changing thermostat settings. other times, the repair costs can be more severe, like having to replace refrigerant coolant.

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As suck, it’s crucial to investigate the cause of your issue immediately, as catching problems early often reduces the severity of the damage. Conversely, sometimes AC unit output is too cold, and AC owners often need to figure out why an AC is spitting out ice.

Check Thermostat Settings

The first thing to do whenever you feel hot air coming from your air conditioning is to check the thermostat. Make sure it’s set to the desired temperature. And a great way to avoid further issues is to place it on AUTO mode.


Never leave any object in the way of your air conditioner vent. Blocking the vents prevents warm air from being removed from the house; this can contribute to AC damage.

Refrigerant Leak

If your air conditioning unit is leaking or has low refrigerant levels, it has no way to cool the air that passes through. As a result, the unit will blow hot air.

While it’s always best to contact a professional to help recharge or fix a refrigerant leak, it’s possible to do it yourself. Those looking for guides can find our article explaining what type of freon to use for a home air conditioner.

Dirty Air Filter

STAT: Failing to replace your unit’s air filter regularly can decrease overall efficiency by up to 15%. (source)

Dirty air filters can cause several AC issues, such as why a portable air conditioner is leaking water. A clogged AC filter blocks airflow, preventing the unit from adequately removing warm air and distributing cold air. Always check your filters to make sure they are clean and free of damage.

If you think your air conditioner is beyond repair and are looking for your next device, check out our guide to the best 15000 BTU window air conditioners.

Why Is My Air Conditioner Blowing Hot Air FAQs

How do I know if my condenser coil is frozen?

Remove the front panel on window air conditioners and portable units to check the coils; on central outdoor units, you must unscrew the side panel.

What can I do to prevent my air conditioner from blowing hot air?

Performing routine maintenance checkups, proper winter storage, and changing the air filter are the best preventative measures any AC owner can take.

How much does it cost to recharge the air conditioner refrigerant?

Recharging the freon can cost anywhere from $200-$600.
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