How to Test a Pool Pump Capacitor

Swimming pools function on the back of a lot of complex equipment, such as the pool pump capacitor. The pool pump capacitor is sort of similar to the battery of the car—it gets the pump running and up to speed before the pump switches to another power source. Now and then, you may need to test it to ensure it is still running smoothly.

In this article, I will go over my step-by-step process for testing your pool pump capacitor, how to tell if your capacitor is faulty, and more.

Main Takeaways

• To test the capacitor, all you need to do is find and discharge the capacitor, set the multimeter, and test it.
• If you are not comfortable testing or replacing the capacitor yourself, hire a pool professional to do it for you.
• Pump capacitors are mostly inexpensive and easy to replace.

Step-by-Step Process: How to Test a Pool Pump Capacitor

Is your pool pump not running as it should? One of the first troubleshooting steps you should take is to test your pool pump capacitor. By testing the capacitor, you can potentially avoid replacing your entire pump, saving you a lot of money!

Note that capacitors don’t last forever. Generally, a standard pool pump capacitor is only good for 5,000 starts before it goes bad, so if you’ve had your pump for a while, the capacitor may be due for a change.

Testing a capacitor is pretty simple. You will need:

• A multimeter
• An insulated screwdriver
• A rag 

Step One: Find the Capacitor

Before you get started, turn off the power completely to avoid any electrical hazards. Then, locate the capacitor, a small, cylindrical metal object usually mounted near the pool pump motor.

Step Two: Discharge the Capacitor

You will now need to discharge the capacitor to prevent any electrical accidents. Remove the cover plate, and briefly touch the two terminals of the capacitor using your insulated screwdriver. You may experience sparks or popping sounds as it drains.

Step Three: Set the Multimeter

Get your digital or analog multimeter out. Set the test meter to Ohms of 1k or higher.

Step Four: Test the Capacitor

Touch both leads of the meter to the capacitor terminals. If the meter rises slowly, your capacitor is functional and capable of holding a charge. If the meter reads 0 and stays that way, the capacitor is faulty and needs to be replaced.

There you go! As you can see, testing a pool pump capacitor is a super simple process. However, if you’re unsure about testing the capacitor, you can always hire someone to do it for you.

Can You Test the Capacitor Without a Multimeter?

No, you cannot. It’s not possible to test a pool pump capacitor without one. Keep in mind that a multimeter is a necessary tool for testing anything electrical, allowing you to measure resistance, voltage, and capacitance, all of which are parameters useful for determining whether the equipment is functioning correctly.

Without a multimeter, you cannot accurately measure the electrical properties of the capacitor. And since acquiring a multimeter is fairly simple and easy, I recommend keeping it handy in your pool shed or garage. You don’t need a fancy multimeter; you can find one for as cheap as $15!

If you’re adamant about testing the capacitor without a multimeter, one option is to simply replace the capacitor with a new one. Doing so will help you determine whether or not the capacitor was really the issue. Replacement capacitors do not cost very much, so this can be a potential solution.

How to Tell If Your Capacitor Is Faulty

Here are some signs to look out for that may indicate that your capacitor is faulty.

Bulging

Take a look at the capacitor. Is it bulging or looking misshapen? Are there any signs of cracking? If so, the capacitor is in bad shape and should be replaced ASAP.

Use Your Ear

A clear sign of something wrong with the capacitor is usually an odd noise, such as unusual humming or buzzing. This can occur because the capacitor is not able to store the electrical charge properly, causing the current to surge in and out of the device rapidly.

Overheating

While it is normal for pool pump motors to get hot, a faulty capacitor can lead to overheating. When a pool pump overheats, it will likely shut down immediately to prevent any issues. So, if your pool pump runs but suddenly turns off after some time and your motor is very hot, you might have a faulty capacitor.

Use Your Nose

When your pool pump tries to turn on, if there is a burnt rubber smell in the air or another strange smell coming from your motor, it could be a sign of a faulty or dying capacitor.

Intermittent Operating Ability

A faulty capacitor may cause the pool pump to operate with bursts and sputters, primarily because the capacitor cannot provide a consistent starting supply of electrical energy. If your pump struggles to start, test the capacitor first to see if that’s the issue. If that’s not the case, here are some other common pool pump issues you should look out for.

Equipment Failure

Is your pump failing to start at all? A faulty capacitor may cause complete equipment failure if it can no longer store any electrical energy. Test your capacitor as per the steps explained above to establish whether it needs replacing. Otherwise, you may need to replace the entire motor.

How to Replace a Pool Pump Capacitor

As mentioned above, a pool pump capacitor is usually good for 5,000 starts. While that sounds like a lot, it does tend to get used up surprisingly quickly. Fortunately, a capacitor can be replaced for a fraction of the price of a new pump motor. Here’s how to do so:

1. Turn off the power to the pool pump. To be absolutely safe, turn all the power off at the circuit breaker. 
2. Locate the capacitor, a small cylinder under the cover plate held together by two screws. Remove the screws and the cover plate to access the capacitor.
3. Using your insulated screwdriver, discharge the capacitor. Wear rubber gloves and protective eyewear as a guard against any sudden popping or sparking. Test the capacitor with a multimeter, and make sure it’s at 0.
4. Free the capacitor by removing the motor leads, making sure you know exactly where everything goes when you eventually put in the replacement. To help, take photos of the placement of the leads so that you can restore them to their original position after you reconnect them.
5. When replacing the capacitor, you have to make sure you replace it with one that has an identical rating. Always replace a bad capacitor with a model that has the same voltage. If you must, always use one with a slightly higher voltage. Never use one with a lower rating.
6. Reconnect the motor leads to the replacement capacitor and fasten the capacitor in place as required.
7. Use a multimeter to verify if the capacitor is in good working condition.
8. Replace the cover, turn the power back on, and then run the pump to check if everything is working correctly.

If you’re in doubt at any point during the process, you can always call a professional to replace the capacitor for you. After all, better safe than sorry when it comes to anything electric!

Frequently Asked Questions

Will the pool pump run without a capacitor?

A pool pump can technically run without a capacitor in some cases. However, keep in mind that doing so can seriously damage the motor, shortening its lifespan. It might even cause the pump to severely overheat, which could lead to a fire hazard.

What happens when the capacitor goes out on a pool pump?

When the capacitor goes out on a pool pump, it can cause the pump to stutter, not start, run poorly or at a reduced speed, overheat, or make a humming or buzzing noise.

How much does it cost to replace a pool pump capacitor?

Replacing a pool pump capacitor typically costs between $10 and $30. Of course, the actual cost itself will vary depending on the brand, capacitance, and voltage.

Capacitors: The Secret to a Healthy Pump

While they may not look like much, capacitors are essential to the smooth start and functioning of the pump – don’t underestimate their usefulness! Luckily, they’re easy to maintain, test, and replace when needed, so you should be set if you run into any issues with them!

If it’s time for you to replace your pool pump entirely, here are my favorite pool pumps.

Any more pool-related questions I can help you with? Let me know; I’ll be happy to answer your questions.