Why Is My AC Blowing Hot Air?

The warmer it is outside, the more frustrating it will be when you turn on your AC and get hot air blowing through the vents.

Something’s wrong, but what is it? And, how hard — or expensive — will it be to fix?

There could be any number of problems, ranging from a simple user error to needing a completely new system. But, the good news is that we can help you pinpoint the issue. And, in some cases, fix it yourself.

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Before we go any further, however, we stress that you shouldn’t take anything apart of fiddle with any electronics! You could damage your system, or — much worse — hurt yourself. Don’t hesitate to call us here at Air Comfort technologies if you notice anything that’s not a simple fix.

Four Possible Reasons Your AC is Blowing Hot Air

If you’re getting hot air instead of cooling from your AC, the problem could be:

  • The Thermostat Isn’t Set Correctly
  • The Thermostat Is Damaged
  • The Drain or Air Filter Is Clogged
  • Coolant Is Low or There’s a Leak

We’ll start with the possible DIY fixes.

The Thermostat Isn’t Set Correctly

If your thermostat is set to “Heat” or “Fan Only,” you won’t get the treatment you want. And, this problem occurs more often than you may realize. People often turn on the thermostat and set the temperature, but forget to switch it over from their winter setting.

Now, if you’ve got it turned to heat, you likely won’t get cold air. The system won’t do anything until it gets colder than your call setting. More common in this case is that “Fan Only” or “Circulate” setting. In this case, you’re running just the fan, but not the heater or AC.

This setting is useful in the spring and fall when your windows are still closed, but you want some fresh air. It circulates the air without affecting the temperature. If it’s hot in your house, hot air comes through the vents.

So, check your thermostat first to make sure all the settings are where you want them.

The Thermostat Is Damaged

It’s also possible that you’ve set your thermostat correctly, but there’s a problem with the unit itself. This could be the wiring, low batteries, and — in older models, anyway — calibration issues. It’s a little harder to diagnose, but you can check a few things.

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First, replace the batteries. If that doesn’t help, use a thermometer to see if the temperature right near the unit is the same as the display. The problem could be that it’s not reading the room correctly.

The last thing you can do is carefully remove the thermostat and check the wiring. You should see colored wires connecting to ports on the back that are labeled with those colors. If there’s a mismatch, then the thermostat may be turning on the furnace when it wants the AC.

The Drain or Air Filter Is Clogged

The general rule of thumb is to change your filter every three months. But, really, once a month is ideal. That’s especially so if you have pets or a lot of dust in your home. All those particles will clog it up faster than usual.

When the filter’s clogged, the system stops working correctly. Most times, that results in weak or no air circulation. It happens when your system isn’t strong enough to push the air through a clogged screen.

Other times, you get warm air through the system when you’re looking for cooling because it’s not drawing warm air properly from the home to get cooled.

Or, you’ve tripped a fail-safe in the AC. The unit recognizes something’s wrong and stops working. At that point, you’re not cooling the air, and it’s coming back out of the system as warm as it went in.

So, replace the filter and see if that helps. If the cloth screen is grey or darker, then you need to change it more often.

Another possibility is the drain, which is part of how your system removes moisture from the air. As the water vapor condenses, the drain removes the liquid from your home.

But, if that drain gets clogged, you’ll end up with problems. Those issues include warm air coming through the vents, partly because the system now can’t dehumidify the air as it’s supposed to.
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 Coolant Is Low or There’s a Leak

A common culprit for an AC blowing hot air is a coolant problem. As air passes through the system, the refrigerant liquid, or coolant, plays a crucial part in removing the heat from it. That way, when it returns through your vents, it’s much cooler.

22If you’re coolant’s low, likely due to a leak, then the air in your home is passing through your system, but there’s nothing cooling it. So, it’s just as warm as when it went in there.

You can’t repair this yourself. If your AC is more than a decade old, it could be a bigger problem — more on that here.

But, you can check to see if this is the problem. And, the sooner you catch it, the better. If you don’t lose too much coolant, you might avoid having to replace an older unit. And, in any case, the less we have to recharge the system, the better.

Check the outdoor condenser for any visible frayed or broken wiring or connections. Listen for a hissing sound or a sweet chemical smell. That will clue you into a leak.

Air Conditioning
If your AC is blowing hot air, don’t wait around! If you let the problem go, it will likely get worse. And, it’s possible that it’ll get bad enough to ruin your entire system.

If you can’t locate or fix the problem yourself, call Air Comfort Technologies for air conditioner repairs in and around York, PA. We’ll get to the root of the problem and have your home cool and comfortable again as soon as possible.

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