How to Test Air Conditioner Capacitors

Introduction:

Air conditioners are a necessary evil during the summer. Unfortunately, they can also be expensive to run. One way to reduce the cost of cooling your home during the summer is to ensure your air conditioner is running at maximum efficiency. One way to do this is to test the capacitors. In this post, we'll show you how to test air conditioner capacitors using a multimeter.

KEY TAKEAWAYS

When your air conditioner is on the fritz, it’s important to know what’s wrong before you call for service. One common issue is a faulty capacitor. This component provides the initial power boost to an outdoor AC unit as it begins its cooling cycle. If it’s not functioning properly, your AC unit may not turn on at all or it may not be able to cool your home. Luckily, testing a capacitor is a relatively easy process and you don’t need any special equipment. You’ll need a multimeter and a basic tool kit, which you can probably borrow from a friend or neighbor. Capacitors usually need to be replaced around every twenty years, so if your AC is on the older side, it might be time for a replacement.

Insider Tip

There are a few ways to test air conditioner capacitors. One of the easiest is to check if the capacitor is visibly damaged. If the top of the capacitor looks like a pop can that's been pushed up, then it's likely that the capacitor has blown. Another way to test capacitors is with a multimeter. By measuring the resistance across the capacitor, you can determine if it's blown or not. Finally, you can also use a continuity tester to test for continuity across the capacitor. If there's no continuity, then it's likely that the capacitor has blown.

What is an AC Capacitor?

An AC capacitor is a small silver cylindrical object with three wires connected to the top. It stores energy and delivers a large power boost to the motor, which kicks off the cooling cycle. If your air conditioner isn't cooling properly, it's worth checking the capacitor to see if it needs to be replaced. You can test it yourself using a multimeter, or take it to a professional to have it checked.

STEP 1 Turn Off the AC System’s Power

The first step in testing capacitors is to turn off the power to the AC system. This will help prevent injuries and protect the equipment.

STEP 2 Find and Inspect the Capacitor

Now that you have located the compressor, you need to find the capacitor. Unscrew the access panel and look for a cylindrical object with two wire leads coming out of it. This is the capacitor. Do not touch the capacitor at this point of the procedure.

STEP 3 Discharge the Power in the Capacitor

involves discharging the capacitor. This is done by disconnecting three wires: Herm, Fan, and Common. The wires will be labeled on the capacitor. Make sure that the wires are not touching one another after they are disconnected. Note down which wire attaches to which wire post.

STEP 4 Dismounting the Old Capacitor

To dismount the old capacitor, unscrew the bracket on the capacitor terminal. Then, pull out the capacitor. Be very careful not to touch the capacitor terminals, as you could get a nasty shock. If the capacitor is corroded or swollen, it's best to call in a professional to replace it.

STEP 5 USE MULTIMETER TO TEST THE CAPACITOR

Once you have located the capacitor, it is time to test it. This is a simple process that only requires a multimeter. Set your multimeter to the capacitor testing mode. Modes are explained on the device’s user manual, but it is usually located in the 12 o’clock position. Next, check the capacitor label for the target numbers. For example, it might say 35uF/5uF. Place the red probe on the herm post (H) and the black probe on the common post (C). The number that shows up on the multimeter display should be the same as the first number (like 35uF) on the label. If it’s not, then you have a bad capacitor and it will need to be replaced.

STEP 6 Reassembly

If your capacitor passed the test, screw it back into the bracket. Reconnect the wires and screw the access panel back on. Turn the AC power back on and check to see if your unit is running properly. If it's not, you may have to call a professional to come take a look.

Conclusion:

If you are having trouble with your AC system, it is important to test the air conditioner capacitors. By following these simple steps, you can test the capacitors and determine if they need to be replaced.