Why Is Air Coming Out Of Vents When AC Is Off?

Are you one of those who are currently experiencing trouble in their unit? Specifically, because the air is coming out of the vents when your air conditioner is off? If so, then you have come to the right place! We did the research to bring you the answer.

One possibility for this issue is that the unit has electrical problems. It's also possible that you may have accidentally set your air conditioner's fan setting to On instead of Auto. Lastly, it may be your thermostat that causes the problem.

Although we think it is better than having an air conditioning unit that won't turn on, this issue still means trouble. So, if you want to know if you can solve this problem alone, we suggest you keep reading until the end of this post to know how to and learn more about air conditioners problems. Without further ado, let's get into it!

HVAC return air wall vent, Why Is Air Coming Out Of Vents When AC Is Off?

Why Is Air Continuously Coming Out Of The Vent?

An air conditioner that continuously blows air even when turned off is troubling. What's more, it still consumes energy.

Inspecting a home air vent for maintenance


There are three leading causes of this particular issue, and they are:

1. Electrical Issues

The wiring or the parts of an air conditioner are usually the cause of problems. And these typically require the help of a licensed professional. However, before calling a professional, you might want to check your air conditioning unit beforehand.

Man checking the wire of the air conditioner

Check for these electrical issues. There is a possibility that one of them causes the continuous blowing of air when the air conditioner is off.

Contactor Issues

It is the part of the air conditioner that controls the flow of electricity into its components, especially the compressor itself and the condenser.

When the air conditioning unit begins the cooling process, the contactor will let the electricity go along. It will continuously do this until the thermostat reaches the target temperature.

If you are not performing regular cleaning and maintenance for your air conditioner, once it gets older, it may get stuck. It will continue to send electricity to your unit's parts that will prevent it from turning off even if you try to turn it down.

In addition, it is common for bugs to get into the air conditioning unit, which may cause the malfunctioning of the contactor.

Diagnosing this issue and the repair process require extensive knowledge and training. You may want to contact an HVAC professional for this one.

The Fan Motor Is Burnt Out

When your air conditioning unit is turned on but is not delivering enough airflow, either or both the indoor and outdoor fan motors are the problem. It is likely that it is burnt out.

Overworking the fans of an air conditioning unit and a lack of maintenance can undoubtedly cause a problem. If the fans are not working, the air conditioning process will not be complete. In addition, an overworked fan motor can lead to operational abnormalities.

To conclude, a damaged fan motor will lead to total airflow issues such as your current problem.

Run Capacitor and Start Capacitor

There are two capacitors that an air conditioning unit has. Their purposes are like a battery; one is to store energy, and the other uses it on power-intensive processes.

When you start the air conditioner, the start capacitor will use a blast of energy to send signals to the motor. On the other hand, the run capacitor stores the power to keep the motor running.

Both of these capacitors are really important, and they can be the cause of your air conditioning problem if they are damaged.

The Circuit Breaker is Tripped

This problem is simply a power issue. It is typically because of an overheating circuit breaker, making the air conditioner stop running. You can fix it in a minute by flipping the switch at the breaker. However, it could be something worse.

You might need the help of a professional in this case, especially if it trips continuously.

Wire Issues

The air conditioner's wires can get damaged over time. Several things cause this, including amateur repair jobs, wear and tear, and power outages.

Damaging the air conditioner's wiring can cause short circuits or disconnection from anywhere in the unit.

Problems With The Fuse

Sometimes, a fuse problem exists when your repairman positions the wrong fuses in your unit's system.

Another reason is the cleaning and maintenance of the fuse. It may have been quite some time since the last cleaning. Perhaps some dust and debris are already interfering with your fuse's connection.

2. Accidentally Turned On The Fan

There are some instances where, when cleaning, you can accidentally turn something on.

For example, for your air conditioner's fan, you may have turned its fan setting to On instead of Auto. Switching it on can cause your fan to blow air continuously even if it is off. If you notice that this is really the problem, you need to switch it back to Auto.

3. The Thermostat Is Old

This issue is not as common as electrical problems. However, like any electrical unit, a thermostat can deteriorate and fail. Typically, it can last up to 10 years, but it can start malfunctioning due to gradual changes along with general aging, wiring issues, or dust buildup.

Relay switches can become jammed or damaged over time, making it impossible for the thermostat to communicate with the fan. It indicates that the fan is not getting the commands you are sending to the thermostat.

As a result, even if your air conditioner is switched off, the fan will continue to operate. Specifically, it will continually send air to your vents even if you constantly try to turn it off.

In addition, it is not common for thermostats to run off while the air conditioning unit is on, but there's a possibility that it could happen. Be informed that problems may still occur even if the thermostat is entirely new.

If your thermostat is acting up, we can provide you with some tips you can try before calling an HVAC professional. Read the information below:

Replace The Batteries

If you own a digital thermostat, you can change its batteries and see if that will resolve the problem. Replacing the thermostat's batteries with a new one every year is a must.

Clean The Thermostat

This will apply to mechanical thermostats. The standard mechanical thermostats include a manual lever that modifies the room's temperature. This kind of thermostat can quickly accumulate dust that will lead to malfunctioning.

A typical home heating thermostatic control dial on a wall

To resolve this problem, remove the thermostat cover and wipe the insides. You can also use a small brush to clean it. Make sure to clean it as gently as possible.

Check The Wires

Tthermostat that is being installed on this drywall for a new renovation

Detach the thermostat cover and inspect it to make sure that the wires are still in their proper place and firmly attached to their mounting screws. If you have noticed several disconnected wires, immediately call a heating and cooling specialist to get everything working well again and prevent further damage.

Click here to see this Emerson thermostat on Amazon.

To Wrap It Up

Like any other HVAC system, there are inevitable situations where your air conditioning unit will act up. That is why HVAC professionals highly advise every homeowner to keep the air conditioning units well maintained to get the most out of them.

If you found this article helpful, check out these excellent related articles about air conditioners:

How Long Is The Exhaust Hose On A Portable Air Conditioner?

How To Clean A Portable Air Conditioner [Including Coils And Water Tank]

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  1. “An air conditioner that continuously blows air even when turned off is wasting energy, increasing the risk of fires, and damaging people’s health. Thank you for listing down the reason behind this issue and some quick solutions too.

    Calling professionals for any air conditioner related issue is beneficial for maintaining the system. Thank you for sharing the article.”

  2. Live in a three year old townhouse with central AC. When I turn the second foor AC on, the first floor AC comes on-the thermostat on the first floor is completely turned off and fan is on auto mode.

  3. Holy cow! I completely lost my mind trying to figure out why there was air coming out of vents and was trying to do a temp fix by taping up cardboards on the vents. Never thought the fan was turned on!! 🤦‍♀️ It was getting way too cold haha
    Thank you!

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