Updated at: 06-05-2022 - By: Sienna Lewis

If your air conditioner continues to run even after you have shut it off, you may have a faulty thermostat. It is also possible to activate a constant running air conditioner based on the unit’s settings. You may be able to remedy the problem by altering the thermostat settings, but it’s more likely that you’ll need the help of a professional.

Why Window Air Conditioner Keeps Running When Turned Off?

The following are five likely explanations for why this is happening:

1. Problem With Its PCB Assembly

A PCB or Electronic Control board, as it is more commonly known as, is responsible for controlling the functions of each of the window air conditioner’s components. Sensors in the control board measure your room temperature and transmit it to the thermistor device.

The fan and compressor circuits get commands from the board’s output relays after it receives the data. The output relay will signal the fan and the compressor to turn off if the room temperature has already reached the setpoint. It, on the other hand, will encourage them to keep going.

A malfunctioning output relay could be to blame if either the compressor or the fan continue to run after the setpoint temperature has been reached. Such a circumstance necessitates a total board replacement.

There are some window air conditioners, however, that have a separate relay board from their Electronic Control Board. The sensor in your air conditioner may need to be checked for damage or a faulty connection with a multimeter before the circuit board can be replaced if that is the case.

2. Problem With The Thermostat

If your window air conditioner continues to blow chilly air even after you’ve shut it off, there may be a problem with the thermostat in the unit. Known as temperature control in the general public, the thermostat uses internal electrical contacts to power the compressor circuit.

Additionally, a bulb sensor and a capillary tube are linked to the evaporator coil, which measures the temperature of the surrounding air. Any time the sensor detects a drop in temperature, the switch contacts should be opened, cutting off the compressor’s electricity supply.

In a perfect world, this is what would happen. In some cases, if the connections are stuck or welded shut, the compressor may continue to run even after the sensor has sent the command that the desired room temperature has been obtained.

To be sure, you’ll have to have a look at the sensor bulb. Repairing the thermostat may be necessary if the sensor is working properly but the compressor continues to run even after the window air conditioner has been switched off.

3. Problem With The Temperature Sensor

Temperature sensors are included on all window air conditioners (thermistor). Even though you can’t see the evaporator’s room-facing side, this device is located on the evaporator’s room-facing side.

The sensor, as its name suggests, is primarily designed to measure the temperature of your environment. Using this information, the compressor can decide whether to keep going or stop based on whether or not the necessary temperature has been attained yet (if your room is already cold enough).

As a result, we’ve observed a number of window air conditioners with malfunctioning temperature sensors. Because of this, the compressor, which relies on the sensor to activate and deactivate, is still churning out cold air.

A multi-meter and technical specifications of your window air conditioner’s thermistor are required to test the sensor. Examine the circuit board once you’ve got them. Sometimes a sensor will still function well even though the connection to the control board is slack.

4. It’s Too Hot Outside

Even if you don’t want it to, a window air conditioner that is too small to chill the area will continue to run. Do you understand why? Because the system won’t be able to reach the temperature you set it to.. When it’s hot outside, this problem tends to pop up.

A larger-size window air conditioner or a wait till the weather cools down are the options you have if that is the case. Maintaining your air conditioner, no matter which method you pick, is essential. That would reduce the compressor’s workload.

5. Short-Circuiting

When your air conditioner was running normally, were there times when your electricity usage spiked? Have you heard from a neighbor that some of their electrical appliances have been damaged by an increase in voltage?

If your answer to any of these questions is in the affirmative, then your air conditioner might have short-circuited. There’s a problem with the cables that connect the thermostat to the blower. When you switch it on or off, the commands don’t get to the blower. Calling a local HVAC company may be necessary in order to address this problem on your own.

Is It Normal For My AC To Run All Day?

It is possible that your air conditioner has short-circuited if you answered yes to any of the following questions. Because the wires that connect the blower to the thermostat may have burned, the commands aren’t getting to the blower when you switch it on or off. You may need to call a local HVAC company to solve this problem.

Air Conditioning Systems: How Do They Work?

Our goal is not to seem overly academic and so bore you to death.

You should appreciate the fact that most air conditioners today can operate without the need for any intervention from you.

In order to keep your house livable, your air conditioning unit relies on a complex network of circuit boards, cables, fans, and other components. The fan and cooling system will be the focus of our talk today (this is where the problem is likely to be).

Temperature control is the primary function of the cooling system. Once you’ve selected your chosen temperature, the cooling system (also known as the EBC) receives the data and passes it forward to other AC components.

The cooling system (electronic portion) is aware of this and tells the fan to run and draw in heated air from the room to cool it down. Fans are once again instructed to circulate cooled air back into your home after cooling.

The two systems must work together and turn on and off at the same time for a well-functioning air conditioner. Although the cooling system has been turned off, the fan may continue to run. If your thermostat is set to “on,” this is most likely the situation. The fan will continue to run indefinitely to keep your room at the ideal temperature. Simply set your thermostat to “auto” to turn it off.

Try These DIY Fixes

While you’re waiting for your HVAC specialist to arrive, take a look at these potential trouble places around your system. It’s more than likely that this will merely serve as a band-aid for a more serious problem. This will, however, allow you to get your unit back in order until an expert can come in and inspect it properly.

Check Your Thermostat’s Settings

Even before you call a heating and cooling specialist, you should check your thermostat settings. A easy, free answer to your difficulties can be found using this method. If you mistakenly reset your thermostat, it could cause your air conditioner to run constantly.

To see if the thermostat is working properly, set it to a temperature that is similar to the one in the room. The AC should be alerted to the change in settings and shut down the airflow.

As soon as this doesn’t go away, you’re probably dealing with an issue unrelated to your thermostat. An expert HVAC technician can quickly and readily detect the problem at this point.

My Window Air Conditioner Keeps Running When Turned Off: What To Look Out For

There are a few reasons that can convert your air conditioner into an electronic zombie, as we described previously. We took a step further and talked about the workings of your air conditioner. To get to the bottom of the issue, we’ll need to go a little deeper into the technical side of things.

You need to check these three things:

  • Board of Electronic Controls (PCB Assembly)
  • Setting the Right Temperature
  • A thermometer is a thermometer (Temperature Sensor)

Your air conditioner is in significant danger if everything appears to be in order but you’re still having this problem. To have your air conditioner repaired, simply call the local Phoenix experts you always have on hand.

The Electronic Control Board (PCB Assembly)

If your air conditioner keeps running even after you turn it off, you may have a defective electronic control board. This is the air conditioner’s command center, as the name implies. It may even be referred to as the “brain” of an air conditioner, according to some. It receives and transmits data to and from various AC components.

The electronic control board turns on the cooling system (compressor) and fan when the thermostats detect a high temperature in the room. If the fan and compressor continue to operate even after the ideal temperatures have been reached, the PCB is likely to be at issue.

Replacement PCBs are the only choice if your PCB has been damaged.

Temperature Control

The thermostat is sometimes known as “temperature control.” Thermostats are little devices that monitor the room’s temperature and transmit that data to the Electronic Control Board. Most of the time, they’re in charge of air conditioner automation.

Even if you turn off your air conditioner, it may still be running due to stuck knobs (relay switches). Rotating dial thermostats are frequently the culprit here. If the temperature in the room rises above a certain level, the dials normally meet and the compressor is activated. Compressors are designed to operate even when temperatures are optimal, but if they become stuck, they will continue to run (air conditioner switched off).

Thermistor (Temperature Sensor)

Both the thermistor and the thermostat are involved in determining the temperature of a room. It’s usually a little bulb near the evaporator on window air conditioners. Thermal sensors are used to determine if a cooling system should be activated or deactivated, just as thermostats.

If your window air conditioner continues to run even after you’ve shut it off, it’s possible that you have a malfunctioning thermistor. Checking the sensor for damage or disconnecting it is the best course of action. Inspect the relay board and other components of the ECM of your air conditioner with your multimeter while you’re at it.

Inefficient (Undersized) Air Conditioner

This is a non-technical issue, unlike the others we’ve discussed. You’ve picked the wrong room/home air conditioner (In most cases, an undersized air conditioner).

The term “undersized air conditioner” refers to a situation where the air conditioner is too small for the room it is being used in (air input is more than output). As a result, your air conditioner is unable to maintain a consistent level of cooling in the room, and will continue to run ineffectively even when the device is switched off. Only a more powerful and larger air conditioner will do in this situation.

When it comes to air conditioners, efficiency and sizing are critical considerations. Decide wisely and avoid regrets later. If your air conditioner is too small, you may also encounter additional issues with ventilation. Check out this site for more information.

My Air Conditioner Is Running But Not Cooling Room

An additional situation that is extremely similar to the one described earlier in this article is shown here. Even if your thermostat is working perfectly, it’s more difficult to figure out what’s going on (at least on the outside). In addition to the fact that your AC isn’t working, you’re also losing money in the form of utility bills.

If your AC isn’t working, there are three methods you can troubleshoot it:

  • The thermostat should be checked. Make sure it’s turned on and in good functioning order before you begin using it
  • It’s a good idea to clean the evaporator coil (especially the air filters)
  • Look for symptoms of short-circuiting on the Electronic Control Board (black traces and burnt smell)

Even if the thermostat is set to “cool,” your house isn’t getting any cooler. Find out how to solve it right now.

Conduct Regular Air Conditioner Maintenance

It’s a little-known fact that preventative maintenance can save you a lot of headaches and money. More air conditioning issues may have been averted if individuals paid more attention to their air conditioners, which is something you may not realize. It won’t cost you much either in terms of time or resources.

For Phoenix residents, our 40-point annual checkup will ensure that your air conditioner is in peak working order and alert you to any potential problems.

Note: It’s recommended that you change or clean the filters in your air conditioner on a monthly basis. If your air conditioner isn’t working properly, click here to learn more about troubleshooting it.

My air conditioner keeps running in the evening when the outside temperature cools down. Is that normal?

Even if the temperature outside your home drops in the evening, it’s not clear if that means you’ll need less air conditioning inside your house. Take into account how well your house holds heat. Concrete, for example, is better at holding heat than other building materials, which may necessitate the use of your air conditioner when the sun sets. You may want to buy a separate thermostat and move it around your home at night to determine how accurate your air conditioner’s wall-mounted thermostats are; they can be inaccurate.

What should you check for when your air conditioner keeps running all day?

Because these are “the low-hanging fruits,” your electronic control board, temperature sensing and control should be checked. Follow the above-described procedures to be sure you’ve covered all your bases. Get in touch with your local HVAC professionals if you can’t find a problem with these components and they’ll be most qualified to aid you.


You may have tried to switch off your air conditioner, but it continues to run for one of five reasons. In addition, there could be an issue with the PCB assembly, a malfunctioning thermostat, a malfunctioning temperature control unit, or an internal short-circuiting in your air conditioner’s cables.

If you need help with any of these concerns, we recommend hiring a professional. Although some of you may possess sufficient technical expertise to resolve the issue on your own, it is usually preferable to leave such matters in the hands of professionals. Their experience would ensure that the problem would not reoccur for a long time after they had dealt with it. Contact us if you’d like to learn more.