5 reasons your AC may be blowing hot air

There are many reasons your air conditioning unit could be blowing hot air. Here are a few of the more common ones we’ve found in the Oklahoma City metro area. Some of these you can even diagnose yourself!

Thermostat issues

It may sound silly, but checking your thermostat could save you time, energy, and money! Is it set to “auto” or “on”? If it’s set on the “on” setting, that means it will be blowing air even when your unit isn’t actively cooling the air. That air will feel warm.

It’s a simple fix, though! Just change your setting back to “auto.”

Airflow restriction

This restriction could be caused by a really dirty filter or even dirty condenser coils in the outside unit. The airflow restriction will make it feel like you aren’t getting cool air from your vents. Over time, it will likely cause your outside compressor to freeze up, potentially requiring early replacement of your air conditioning and heating system.

To fix airflow restriction, make sure you’re changing your filters regularly. You can even clean your condenser coils—make sure the power to your unit is off first, though.

Not getting power

When a breaker trips and causes the lights to go out in a room, it’s easy to pinpoint the cause. A tripped breaker could also cut power to your air conditioning unit, though. Your inside unit may even still be running, blowing air that the outside unit isn’t cooling!

Check your breaker box or your fuse box panel to see if this is the cause of your warm air.

Needing refrigerant

Refrigerant is what makes the magic happen. If your unit is low or out of refrigerant, it can’t cool like it’s intended. It might even feel like your AC is broken.

If you suspect your refrigerant is low, it’s best to call a professional. It’s much easier for a professional to find and purchase the right refrigerant for your unit than for a homeowner to, and low refrigerant may even indicate a leak. If there’s a refrigerant leak, that typically means there are some underlying issues that a professional will need to address.

Ductwork issues

This is a less common cause of warm air in the home, but it’s possible that there is an issue with the ductwork itself. In recently built homes, the ductwork is flexible, but older homes have rigid ductwork and are more prone to issues. If something causes the duct to separate a bit, that would allow warm air into the flow and could interfere with your air conditioner’s ability to cool your home properly.

This is another cause of warm air that I’d recommend calling a professional for. But again, it’s not the reason most people have warm air flowing through their unit.

Especially during the hotter months, it’s important to remember that your air conditioning unit will typically be able to cool your home about 20-30° compared to the outside temperature. When it’s 105° outside, it’s highly unlikely you will be able to keep your home at 68° (unfortunately!). You can help your unit last longer by only cooling your home within that range.

If you’re not comfortable diagnosing the cause of the warm air yourself, it’s a good idea to call a professional. We charge $99.95 for a maintenance service, which includes a diagnosis, if you want to tune up your air conditioner.

Many of these issues can be fixed quickly but if your unit is completely not working, let us know when you call—that way we can make the best use of your time!


  1. I’ve heard that the compressor freezing up is one of the most common reasons why air conditioners are blowing hot air. It makes me assume that people aren’t really paying attention to their filters or condenser coils. Although, I’m no expert and could be wrong.

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