Nowadays, having an air conditioner is an absolute necessity, not a luxury. So when the AC does not work, we face a huge problem. The home sweet home becomes hell sour hell! It gets more annoying when the AC seems to be working, and it’s also producing the buzzing sound. Do you know the reason why the outside ac unit is buzzing, but the fan is not running? 

You can’t enjoy the conditioned air because the fan of the AC is not spinning. This article will discuss what you should do when your AC is buzzing but the fan is not running. But let’s discuss some things first so that you know what’s what and can proceed to what needs to be done.

Why Outside AC Unit Is Buzzing, But The Fan Is Not Running

Why Outside AC Fan Buzzing But Not Running?

In most cases, the AC fan fails to run because of damaged AC capacitors. Besides this, a damaged AC fan motor can also cause this problem. Either way, replacing the component is the best solution.

What Is A Capacitor?

A capacitor is a cylinder-shaped small electric component. They store energy like a battery. But they only hold power temporarily. 

We can find two kinds of capacitors inside an AC, a start capacitor and a run capacitor.

For running a fan, you need a relatively low amount of current. But for starting a fan, you need to insert a high power to hit the fan so that it starts spinning. The start capacitor does that for you. It stores a high amount of charge and gives the fan a push. So if your start capacitor is damaged, your fan will not start.

The run capacitor gives a stable supply of power to keep the fan running. If your run capacitor is damaged, your fan may stop spinning frequently or run at varying speeds. 

Why Does A Capacitor Gets Damaged?

Capacitors are similar to batteries. The amount of power they can store drops over time. So your AC capacitors will be impaired eventually. Besides this, high voltage or unstable current can damage them. 

They can also get damaged due to high temperatures, including heat caused by the motor. Regular AC maintenance can increase your capacitor lifespan and help you detect potential defects. 

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Will The Ac Fan Run If The Capacitor Is Damaged?

In most cases, the fan will still run but will be malfunctioned. It will change rotating speeds randomly, and it may also spin slowly or turn off and restart frequently. The fan will take a long time to turn on, and you will feel warm air coming out of AC.

When the capacitor becomes fully broken, the AC fan will not run on its own anymore.

How Do I Know My Ac Capacitor Is Damaged?

There are some common signs of a defective capacitor unit. When your capacitors are damaged, the AC can’t store power. So it will lose energy and need more electricity to operate. As a result, your will have rising energy consumption and costly electric bills. The AC may also make an increased amount of noise when the capacitor is damaged. Now let’s discuss more specifically.

If your run capacitor is damaged, you can find that out easily. If your AC fan stops suddenly or changes speed randomly, you might have a damaged run capacitor.

However, if you have a damaged start capacitor, you will not find that out so quickly. But there are some simple tests for finding out if your capacitor is damaged. We are going to talk about two easy tests here.

Method 1-

  1. Take a long dry wooden stick. A plastic pole should also work. Just make sure the stick is non-conductive. 
  2. Insert the stick in the fan grate and try to move the fan razors. Make sure to spin the razors the way they were supposed to move when the AC is on. Avoid touching the fan grill with your thumbs. Wear non-conducting gloves if necessary.
  3. Look out if the fan turns on and starts spinning by itself.

If the fan starts operating on its own, then you have a damaged start capacitor. Start capacitor gives your fan a push so that it can start spinning. Now you have taken the job and done that by yourself!

If the fan fails to start, then you might have a damaged fan motor. In case you face difficulty with spinning the fan, it means that dust and debris have jammed the fan motor!

Method 2-

  1. Turn off the electronic connection to the air conditioner. You can find the switch at the side of your house near the outside AC unit. If you are not sure how to do that, then shut off the power switch of the house. Flipping off the circuit breaker of the house should also do the trick.
  2. Take a screwdriver and unscrew the service panel on the AC. Keep all the screws in one place so that you don’t lose them later. Then carefully lift the service panel and remove it.
  3. Look for a cylinder-like shiny object with two-three connection pins on the top inside. If you find it, then congrats! You have found the capacitor. 
  4. Carefully look at the condition of the capacitor. A damaged one will show some signs. It could be swollen or leaked, liquid may be coming out of it, it can be burnt and blackened, and the joints may look corroded or rusty. 

If you see any of the signs in your capacitor, then it’s damaged. Please do not touch the capacitor or its terminal with bare hands. Capacitors can store high voltage of electricity. So you can feel electric shock that can even be fatal in dramatic cases. Also, please don’t touch the leaking fluid or try to clean it.

What To Do When The Ac Capacitor Is Damaged?

The short solution

A quick solution to this problem is to use a long pole-like object to move the fan. This will do the work of the start capacitor and give the fan the push it needs to start. But please take safety precautions. Don’t use any conductive material, and don’t touch the fan grill.

But this solution is annoying as you will have to spin the fan with your hands every time the AC turns on. Plus, you can feel an electric shock if you accidentally touch the fan grill. 

The long term solution

The long-term and best solution is to replace the capacitor. You need to contact an HVAC expert to renew your capacitor. And it would be best if you replace it as quickly as possible. 

This is because when your capacitor is damaged, the fan motor will constantly try to turn on. But without the boost from the capacitor, it can’t turn on. So the motor will continue trying, and that causes it to overheat. This heat can damage the fan motor and eventually burn it out. This puts you in need of another costly replacement. 

So quickly replacing the capacitor can save you from more costly repairs that can occur in the future. 

You can replace the capacitor yourself. For that, you should be familiar with electric components and AC functions and have some real-life practice working with them. In this case, you can buy a capacitor and replace it. But we highly suggest hiring an expert for replacement. 

How Much Does It Cost To Replace An Ac Capacitor?

An AC capacitor will cost about 170 bucks on average, and the prices vary from 120$ to 250$. The prices include replacement costs. 

The price depends on the quality, model, voltage, and brand of the capacitor. Branded capacitors can cost you up to 400$ or more. The cost also varies based on the amount of labor required to install the unit. So you can save some money if you replace the unit yourself.

How Do I Know If My Ac Fan Motor Is Broken?

Sometimes, you will notice that your fan is not spinning, but the capacitors seem to be okay. This indicates that your fan motor might be damaged or broken. To be sure, you can look for some signs-

  1. When you try to spin the fan from outside, the blades rotate slowly or at varying speeds. You will find it hard to turn the fan.
  2. When you rotate the fan, you hear a rattling sound. The sound will come from the center of the fan, right where the motor is. 
  3. If you somehow manage to start the fan, it keeps running. It doesn’t stop even when you turn off the AC unit. 
  4. Your fan looks corroded, rusty, or blackened from the outside.

These signs will tell you if your AC fan motor is damaged.

What To Do When The Ac Fan Motor Is Damaged?

Sometimes dust and debris can stick into the motor and cause it to malfunction. The dust particles jam the motor, and the blades can’t move freely as a result. So cleaning the motor may increase its performance.

But when the fan is severely damaged, it goes beyond repair. Then your option is to replace the AC fan motor.

Again, it’s recommended to contact an HVAC professional for replacing your motor. But if you have working experience, you can do that yourself.

How Much Does It Cost To Replace An Ac Fan Motor?

An AC motor costs about 300$ to 600$. It may seem like a lot, but using a damaged fan can damage the AC condenser. A damaged condenser can cost up to 2000$ to repair. So replacing the motor is the best decision.


In this article, we have talked about why the AC fan is may not work when the outside AC unit is running. We have also talked about what to do when this happens. Lastly, regular maintenance can help you prevent most AC-related problems with ease. I hope this article satisfies your quest as to why outside ac buzzing but fan not running.

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