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How To Test Ceiling Fan Capacitor: Comprehensive Guide

How To Test Ceiling Fan Capacitor

Ceiling fans boast various components. The capacitor is one of them, and without it, a fan won’t work. Even if it does work with a faulty capacitor, the blades’ speed would be super low. 

So, the capacitor is a crucial component in ceiling fans. It’s a black box located in the fan’s switching house. 

It’s challenging to know when a capacitor requires a replacement. A drop in a fan’s blade speed could mean a faulty capacitor or a fault in other components. A bad capacitor may even stop the blades from moving. 

However, even if you suspect that your fan’s capacitor is faulty, how do you test it to confirm your claim? 

We will be discussing the various methods in this post. Please note that you don’t need any technical know-how to test a capacitor. Any DIYer can get it done. 

Are you ready? Let’s get to business!

Testing Ceiling Fan Capacitors: Simple Diy Methods And Tips 

You can test your ceiling fan capacitors in various ways. Just get the needed tools and follow the tips below. 

Method #1: Time constant method: 

Let’s discuss the time constant method. It requires a little bit of calculation, though it’s not something you can’t pull off. 

To get started using this method, try to figure out the capacitor’s value. Additionally, you would require a resistor whose value is well-known.  

Now, what does a capacitor’s time constant mean? The time constant means the time it took a capacitor to charge up to 63.2 percent of the voltage applied to the device.  

Here’s how to calculate the time constant. Please endeavor to use this formula as is. 

Time Constant = R X C

T = R (Resistance) multiplied by C (capacitor’s value). 

Now, here’s how it’s done. Have your resistors together with the capacitors connected in series. Then have the circuit connected to a power supply. Please make sure your power supply is delivering a fixed voltage. 

Once you successfully connect the circuit to the power source, start monitoring the time it took the capacity to charge up to 63.2 percent.

Here’s the real deal. From the time and the resistor’s value, you can deduce the capacitor’s value.  

Please take note of this. If the capacitor’s value discovered is closer to the known value, there’s no cause for alarm. It simply means your capacitor is working fine. If the reverse is the case, then the capacitor is bad and needs changing. 

Method#2: Multitester Method

The multitester, also called a multimeter, is an instrument used to measure various electrical properties. This device measures resistance, voltage, and current. That’s why it’s called the VOM (Volt-ohm-milliammeter device)  

If you have a multitester at home, you won’t struggle to detect a bad or good capacitor. You can even use your multitester to test and fix other electrical devices. Technicians use it a lot.  

You can also use a multitester to test a capacitor in various ways. These include the analog multitester, digital multitester, or by setting the multitester in capacitance mode. 

Let’s discuss each process. 

Using analog multitester method: 

Remove the capacitor from the fan. Then charge it to full capacity. Choose the analog meter on your multitester. But please choose ohms, and ensure it’s the higher range.  

Now, get the multitester leads (red and black wire). Connect to your capacitor’s terminals. 

Once you have connected the multitester to the capacitor, pay attention to the reading on the device. 

Here’s the likely outcome. 

If the resistance is meager, the capacitor is shorted. But if there’s no movement or deflection, you have an opened capacitor.  

Finally, if the resistance was initially low but increased to infinite gradually, that’s a sign that your capacitor is working fine.  

Using digital multitester method: 

The digital multimeter (DMM) boasts a similar function as the analog type. The noticeable difference is how the DMM displays its readings. 

If you’re using DMM to test your capacitor’s condition, follow these simple steps. 

Unlike the analog method, you have to discharge your capacity when using a digital multimeter. But you still have to set your multimeter to ohms. Let it sit on the 1000 ohms range. 

Place the multimeter leads (red and black colored wire) on the suspected ceiling fan capacitor. Capacitors usually have two terminals. Place each tip of the meter on the terminals. 

Once connected properly, your multimeter will display a couple of numbers. After that, it will go back to Open Line (OL). But if the reading doesn’t change, you have a dead capacitor. 

Using multitester in capacitance mode:

Please note that not every multimeter has capacitance mode. But if yours does, you can comfortably test your capacity using it. Let’s explain the process.

Your first step is to set your multimeter to capacitance mode. 

Now, charge your capacitor to full capacity. Next, connect the multimeter leads to your capacitor’s terminals. The multimeter should already be in capacitance mode. 

Take note of the reading on the multimeter you’re using. If the reading is the same or close to the capacitor’s actual value, your capacitor is working fine. 

However, if you discover that the reading on the meter is lower than the capacitor’s value, your capacitor is bad and needs a replacement. 

Method#3: Traditional sparking testing method:

If you don’t have a multimeter or other capacitor-testing devices, you can use the traditional sparking process. 

However, you must be extremely careful because the process is quite risky. Only professionals have the knowledge and experience to use this method. 

But anyway, here’s how to go about it. 

Let’s assume you’re making use of a DC supply. In this case, endeavor to use both the non-polarized and polarized capacitor. 

It’s best to utilize a 24V DC supply. Charge your capacitor for a couple of seconds, and take it off the charging source.  

 Now, this is where you need to be extremely careful. After charging the capacitor, use metal to short the two terminals. Ensure the metal object has some insulation to avoid being electrocuted. 

If the capacitor is working fine, you will notice intense sparks. If the reverse is the case, your capacitor has died. 

Can A Ceiling Fan Function Without A Capacitor? 

The capacitor is a small-sized component ceiling fans have. But its importance cannot be overemphasized. 

Now let’s answer the question. Can a ceiling fan function in the absence of a capacitor? The answer is no!

Take away the capacitor, and your ceiling fan becomes useless. The capacitor not only helps to start the fan but enables it to run. 

So, even if you decide to rotate the ceiling fan manually, it won’t work in the absence of a capacitor, even when connected to a power supply. 

Why? The capacitor helps to create a magnetic flux needed for the ceiling fan to rotate. Furthermore, if you have a faulty capacity, your ceiling fan’s speed will reduce drastically. 

So, if your ceiling fan stops working, don’t be quick to get a replacement. The problem could be as little as the capacitor. 

Therefore, consider checking and testing your capacity if your ceiling fan is no longer functioning well or stops working. 


These are the simple ways to test a ceiling fan’s capacitor. From the testing, you can determine if the capacitor is faulty. 

Capacitors are essential components in ceiling fans. And they’re not expensive to buy or hard to find. So, don’t fret when told your ceiling fan’s capacitor needs a replacement. You won’t break the bank to buy one. 

Again, if you want your fan to function as a brand new fan, get a new capacitor. You’ll discover a massive change in your fan’s speed. 

Jacob Lindsey

Jacob is a home remodeling guru having worked over 15 years in construction in Reno, NV, mainly focused on home renovations. He likes taking ideas from his clients and making them a reality.

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