Noticed air coming out of vents when AC is off? – Several pieces of advice on what to do

You may have encountered such a problem for the first time and do not know what to do: the air conditioner is turned off, but the ventilation continues to blow cooled air (or warm air). But the device is completely disconnected from the grid!

How can this be? Let’s all try and figure out what’s going on and what we can do about it.

In short, warm air coming out of vents when AC is off can be in three cases: firstly (it is the most likely option), you could simply forget or unnoticed that turned on the fan; secondly, there may be problems with the thermostat, and thirdly, it could be caused by faulty wiring.

In principle, as a rule, the problem is very easy to solve, but you still need to figure it out. Let’s take a closer look at what is what, what we can do ourselves, and what we can not do without the help of an HVAC professional.

air coming out of vents when ac is off

So why does the air conditioner keep blowing into the vent even though you turned it off?

Of course, this is not the biggest problem in the world, but we must not forget that in any case, if there is air movement, there is also energy consumption for it. And day by day, it will increase the electricity bill.

Reason one (it is the simplest possible): you accidentally set the background of the air conditioner’s fan.

On different models, the options may be called differently, but in general, the fan motor can be forced on, off, or run automatically. Check, whether the furnace’s blower motor is set to “Auto” mode.

It is possible that when cleaning the air conditioner or some other maintenance, you or the master inadvertently put the fan motor in constant operation.

Reason two is the possible electrical faults.

The reason for blowing from the air conditioning vents can be hidden in various electrical air conditioner’s components of the air conditioner.

Of course, in the absolute majority of cases, it is a job for an HVAC professional electrician, and in principle, it is better to entrust this matter to a master.

But still, there are a few simple actions that you can perform on your own, not being an HVAC professional electrician.

Malfunction of a contactor

The air conditioning unit that’s especially vulnerable to breakage is the so-called contactor relay, which regulates the supply and distribution of electricity to any other air conditioning unit of the air conditioner.

Faults in the contactor appear most often due to irregular maintenance of the air conditioner, although there are many reasons for failure for it.

In general, air conditioner pollution by dust, soot, oil, and liquid suspension, and – most often happens – by insects, is one of the most frequent causes of the breakdown of air conditioners.

So if you want the device to work and maintain a favorable climate in your home for as long as possible, do not forget to change the air filters and remove the dust buildup regularly. Of course, a specialist will cope with this best, but you can try to cope with this task.

Noticed air coming out of vents when AC is off? - Several pieces of advice on what to do

Faulty fan motor

Indoor air circulation is supported by two single-directional fans: outdoor and indoor. And if there is a problem with the operation of one of them (usually it is the wear of the outdoor fan motors), the other ceases to adequately handle the load, which may lead to its incorrect operation.

You can try to turn the air conditioner on and off in different modes, noting the air conditioner fan would blow air and its temperature corresponds to the given characteristics.

Failure of one or both capacitors

The moving parts of the air conditioner work in coordination with two capacitors, and both of them are very important.

So, not surprisingly, the output of even one of them disrupts the electrical circuit and leads to a sharp drop in power in the AC system.

This is also one of the most likely causes of poor ventilation movement.

Noticed air coming out of vents when AC is off? - Several pieces of advice on what to do

The circuit breaker tripped

Any air conditioner has a built-in circuit breaker that stops the power supply when the device overheats.

It’s a defense mechanism, and ignoring its signal is pretty reckless, but if the circuit interruption in this node worked, you can reactivate it just by flipping the lever.

But as mentioned above, a circuit breaker may be triggered for a very serious reason, such as a short circuit. So again, it is better to entrust the test and testing of the device to an experienced master.

Damage to the electrical circuit of the air conditioner

Damaged or worn wiring anywhere in the electrical circuit of an air conditioner can also lead to a drop in its power of it, and it starts to blow air continuously. If the problem appears only when the air conditioner is on, it is most likely due to the failure of any part of the electrical circuit.

Identifying a break or wear is a complex process that requires professional knowledge and skills. An amateur can limit himself to a cursory inspection of the accessible places of the electric circuit – there must be no noticeable burnouts and breakdowns.

Noticed air coming out of vents when AC is off? - Several pieces of advice on what to do

Check the thermostat

As we mentioned above, a common problem of any air conditioning system is the wear and tear of the thermostat.

A thermostat is a device that regulates the air conditioner operation according to the specified conditions, in other words, the heating and cooling process.

As a rule, in normal operation, the thermostat works for up to ten years, but it happens that the breakdown happens much earlier.

What can you do? Again, the replacement of a faulty thermostat should be carried out under warranty, in a workshop, by a qualified heating and cooling specialist.

If the thermostat is digital, you should try to replace the battery. In general, the thermostat battery needs to be changed once a year so that all problems can be solved this way. But it only works if you have a digital thermostat, and you can’t do that with mechanical thermostats.

If the thermostat is mechanical, you can try to clean it of dirt and dust. Mud inevitably accumulates on its surface, making it less sensitive to temperature changes, which leads to disruption of its work.

It is easy to clean the thermostat cover, but you need to do it very carefully, with a soft cloth and a brush with soft bristle.

Noticed air coming out of vents when AC is off? - Several pieces of advice on what to do


Why are my vents blowing air when off?

Your air conditioner might start working the wrong way due to various reasons. The most frequent of them are electrical circuit problems, breakage of its components, mainly the compressor, or inaccurate customer settings.

Why is cold air coming out of my vents when the heat is off?

It occurs when the heating coil in an air conditioner has a leak and can be repaired if an experienced mechanic can locate the leak. The problem cannot be fixed and you must replace the current AC unit of the air conditioner. This is only possible when you use heat pumping inside the HVAC system.

Why is my AC blowing air when it’s off?

You may need to remove the A/C blower resistor to control the blower speed of your air conditioner. All parts of this air conditioning process are supplied with electricity and only switches control motor speed.

A summary

Let’s summarize, and again discuss each possible air conditioning unit, which problems can lead to weak movement of air flows in the air vents, even when the air conditioner is turned off.

First, it can be just the wrong thermostat fan setting that you set inadvertently or through ignorance, for example, a fan, inadvertently turned on will cause air coming out of vents. Second, it could be a thermostat malfunction, usually due to contamination of the surface.

And thirdly, it may be caused by the breakdown of the integrity of the air conditioner’s electrical circuit or the failure of one of its components.

If you have checked all the above items and have not found any visible damage in your air conditioner, then the problem lies deeper and requires the help of a specialist.

Do not try to do complex manipulations with the electrical equipment of the air conditioner yourself – it can be dangerous, better contact a specialist.

Also Read: How To Make Your Air Conditioner Last Longer

Robert Brooks

I have an engineering background. I have my own house, where I live with my wife and children. I want to say that the most important thing when equipping a house is to choose the right heating, ventilation, and air conditioning systems.

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