Type to search

Why Your Air Conditioner Fan Keeps Running When Turned Off (And How to Fix It)


HVAC systems are essential to the health of your home. It reduces humidity in your house and makes your home cool. That being said, an air conditioner creates better air quality in the comfort of our homes.

But sometimes, strange noises from the air conditioner fan can catch your attention, making you wonder what’s wrong with it. If you are experiencing the same problem in your air conditioner, keep reading further.

How Does an Air Conditioning System Work?

Air Conditioner Fan

Although air conditioners come in a range of sizes and designs, they all work on the same idea. The air conditioning system is composed of a circuit board, wires, fan, and thermostat, working together to make your home cozy and comfortable.

Air conditioning systems nowadays operate automatically, thanks to the technology that is continuously developing. It is expected to be efficient without human intervention. 

Basically, the cooling system is in charge of temperature control. Once you selected your desired temperature, the cooling system will relay the set temperature to other parts of your AC unit.

The temperature sensor will detect when the actual temperature inside your room exceeds your preferences. The system will instruct the air conditioner fan to avoid extreme temperatures. The cooling cycle will repeat to continuously achieve your desired room temperature.

A modern window air conditioner has two systems that operate the temperature. They work hand-in-hand to switch the setting of the AC. In some cases, it is perfectly normal that an AC will keep the air conditioner fan setting and air conditioner running after the cooling system has turned off if the thermostat is set to ‘On.’

To guarantee an ideal aircon unit and cooled air in your room, simply set your air conditioner fan switch on the thermostat to ‘Auto’ to turn it off. 

Why is my AC Unit Running But Not Blowing Cool Air?

Faulty AC units are called “Zombie Air Conditioners” by technicians as they won’t switch off no matter how hard you try. If your air conditioning unit is behaving like a zombie, you should try to identify the problem by performing a visual inspection. Here are the common reasons why:

Air Conditioner Fan is Switched On

As mentioned earlier, there is a possibility that your air conditioner keeps running because the fan is switched on. In this case, your AC fan is continuously running and not producing cold air. Your AC unit is assuming that the fan motor should continue to operate even after the cooling system is turned off. 

To troubleshoot this, the thermostat must be turned into the ‘Auto’ position to release the air from your AC. Check your thermostat setting to verify if this is the problem. If the Auto mode didn’t work out and your air conditioner keeps running when turned off, your AC might not be working properly. 

Summer Season

Summer months could affect the performance of your aircon, especially when the cooling system can’t reach the temperature you set on the thermostat. This is a common issue with houses that have a small cooling system. In this case, you may invest in a larger and more powerful cooling system or wait for the weather to calm down.

Why Does My Aircon Keep Running When Turned Off?

If your fan keeps running after your system has been shut off and your thermostat is not in the ON position, that fan is telling you that something is wrong with your air conditioner. Your HVAC system may have experienced air conditioning problems that would later damage your unit.

Does your air conditioner keep running when turned off? Here are some of the possible reasons why your HVAC fan continues to run even if it is turned off or in auto mode:

Problems with PCB Assembly

High-functioning air conditioners have an Electronic Control Board or PCB. The main purpose of PCB is to contain a variety of components to carry a certain command, communicate data, or determine the output to regulate the air conditioner.

There are some ACs that have a different electrical system from the unit. Some also come with a separate relay board from their electronic control board.

It is important to remember that even a minor problem with the PCB assembly might harm the components of our air conditioner. This may be the cause of the air conditioner fan not stopping. 

Repairing your PCB depends on the degree of the damage. It requires a skilled professional to fix the PCB to continue using your AC unit.

Broken Thermostat

Your thermostat controls your home’s heating, ventilation, and air conditioning (HVAC) system. If your thermostat isn’t working fine with the temperature, chances are, your AC isn’t either. Make sure your thermostat is working correctly by observing the issues first.

If the aircon doesn’t respond when you adjust the thermostat, a faulty thermostat calibration might be the problem. Another problem you might encounter is when the thermostat doesn’t read the command properly. Your broken thermostat could be unresponsive, producing warm air instead. 

Dirty Air Filter

As an air conditioner can only exhale as much air as it takes in via the return vents, a dirty air filter will limit the amount of released air. This will later cause problems in reading the efficiency of your unit. If you realize your air conditioner fan is producing poor airflow, then your air filter definitely needs cleaning.


The motors in your cooling system are also made to work continuously for long periods of time. However, there are instances when your motors could get overheated, creating a short circuit in your unit.

When electricity takes a “shortcut,” or avoids the usual course, there is a “short” in the internal wiring of your unit, thus creating a short circuit. A short circuit can deviate the electricity. So if this happens, more electricity can flow through, which can cause them to melt, overheat, and perhaps start a fire.

Faulty Relay Switch 

The power supply to the compressor is controlled by an AC relay, which also serves as a switch for the motor. If the damaged relay switch is used, the compressor won’t produce cool air as the AC won’t run without a relay working correctly.

A broken relay switch can perform inconsistently or just shut off. Therefore, your air conditioner is running despite being off may be a potential sign that the relay may be going out.

How to Fix My Air Conditioning Unit?

Air conditioners are intricate to repair. But if you are willing to work around electrical equipment, you can start with your own AC unit.

If your air conditioner keeps running even if it is turned off, listed below are some of the repairs to do to help you with your problem. Here’s how to start:

Clean Your Air Conditioner 

When the cooling fans and coils on the condenser are clean, the aircon is most likely to operate more effectively. By knowing how to clean your aircon thoroughly, you can make your unit work, as well as protect your home from harmful dust.

Change Your Filter Regularly

Air filters increase the performance of your AC system and filter the air properly. However, air filters aren’t intended to last forever. You can either change or clean it, depending on the need of your unit. If you haven’t changed your AC filter in a while, there’s a strong probability that your aircon duct is very dusty. 

You might also want to consider having your ducts inspected to increase the air quality inside your home.

Invest in Blackout Curtains

With the invention of blackout curtains, homeowners can now reduce the home temperature without relying on the thermostat. 

Blackout curtains will assist your AC unit in making your home cool. Not only will this result in a well-functioning AC system, but it will also reduce your energy bills, especially during the summer months.

If these air conditioning repairs don’t work, your local HVAC technician can check your unit and concentrate on finding the more elusive problem. 

Final Thoughts

10/2 or 10/3 Wire

As mentioned earlier, an air conditioner circulates and filters the air inside our room. However, if the system is not clean and maintained properly, an air conditioner might actually worsen indoor air pollution. 

If your air conditioner keeps running while turned off, or your house temperature is lower than the set temperature of the thermostat, it shows that your AC needs repair.

Make sure to give your air conditioning system regular maintenance. It is also best to call your local HVAC company or HVAC professional to repair and fix the issues with your air conditioner. However, an air conditioner that is too old for your house may only be fixed with a complete replacement of your air conditioner unit.

JP Reyes

JP has been in the aircon industry for almost as long as he has been alive. As a child JP would help his tatay fix aircon units at their junk shop in Cavite. After graduating UP in the early 2000's, JP then started his own Aircon servicing business and within 5 years had 10 shops in 8 different cities. Fast forward to today and JP brings all his experience and expertise online to give readers trustworthy advice and reviews about Air-conditioning buying, servicing, cleaning and repair in the Philippines.

  • 1