How to Replace Capacitor on AC Unit for your Home

The main task of a capacitor is to help start the fan and compressor of your AC unit, and a defective one does not do this well.

Usually, about 80% of all breakdowns within an AC unit are mostly because of electrical faults. And the capacitor carries most of these problems. As such, it’s quite crucial to ensure that your AC capacitor is working.

There is a notion that most of the replacement and repairs in an AC unit should be handled by an expert. But, with a capacitor, it is different since you can do it yourself. The only cost you will incur is buying a new capacitor that goes for $10-$20. But, if you involve a technician, you might end up spending something between $300-$400.

The capacitor is viewed as the backbone of an AC.  It is sort of a battery that stores electric current, which starts different components in an AC system. These parts include the outdoor fan, blower motor, and compressor. Therefore, the entire AC unit is in jeopardy if the capacitor fails.

So, do you want to learn how to replace a capacitor on an AC unit? It’s simple! Simply follow the following steps, and you’ll be good to go.

How to Replace the Capacitor on my AC Unit? Crucial Steps

1. Switch off the Power at the Circuit Breaker

This goes without saying. The first thing on how to replace a capacitor on an AC unit is ensuring that the AC unit is turned off.

In normal cases, you will find a local circuit breaker or block fuse in a box outside the AC unit. And to turn off the power, ensure that you shut down the circuit breaker or disengage the block fuse.

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Some AC systems do not have outside shut-off boxes. In this case, you will shut down the power by turning off the circuit breaker that controls the AC. The AC is usually controlled from the main service panel.

Also, turn off the thermostat inside your house. It will block tiny pulses of low-voltage current from being moved to the capacitor as you are operating.

In a nutshell, DO NOT forget to switch off the power of the AC unit. Also, ensure that you avoid moisture when switching off to eliminate the chances of dangerous shocks.

2. Get a New Capacitor

This is the most crucial step when replacing the capacitor on your AC unit.

Before purchasing a new capacitor, you need to locate the current one inside the panel. It usually resembles a small cylindrical can and has a sticker fixed to its side. Take note of all the information on the sticker, including tolerance and load voltage.

Ensure that you purchase a capacitor with the exact specifications. The new one may be in a different shape, but that is not a big deal. What matters is that it will fit in the existing space. You can purchase a new capacitor at your local HVAC store or online through eBay, Amazon, and other platforms.

However, the best place to purchase your capacitor would be in a physical shop. This way, you will be able to evaluate the different brands and their prices. You will also be able to ask any questions that you may have about the capacitor.

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To purchase the right capacitor, get the same model number from the same producer.

3. Remove the Access Panel

Next on how to replace a capacitor on an AC unit is removing the access panel. The panel is found on the upper corner of the AC casing.

Remove the mounting screw using a nut driver to open the access panel. And ensure that the screws and the cover are stored in a safe place.

Be careful as you remove the mounting screws to avoid any injuries.

4. Discharge your Capacitor and Label All the Wires

It is shocking to find out that the capacitor may be holding some electricity even with the power switched off. And for this reason, your next action should be to discharge the capacitor and label the wires. Discharging this current allows you to work on the device safely.

Grab the blade of the insulated screwdriver to discharge the capacitor. This will ensure that there is no electricity left inside the capacitor.

The next thing is to examine the old capacitor. Take note of where the three wires (compressor, common, or fan) are attached.

The old capacitor should have tags that show where each wire proceeds. “Herm” for compressor, “Fan” for fan, and “C” for common.

5. Insert a New Capacitor

This is pretty easy to do. Just ensure that the new capacitor is positioned in the same place as the old one. You can use a mounting strap to ensure that it’s tightly secured. The spade wire connectors should be in the right spots on your new capacitor.

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The connections should also be right; compressor wire to “Herm,” common wire to “C,” and fan wire to “Fan” posts. The capacitor will not function if there are wrong connections, so beware.

6. Switch on the Power and Test

At this point, you must be very eager to know whether the new capacitor is working or not. So, switch on the AC unit. You will do this by either reinserting the block fuse or powering on the circuit breaker. Ensure that the thermostat is turned on too.

Put the temperatures on low settings to ensure that your AC is switched on. If it fails to function, the problem could be with the wire leading to the capacitor. Verify whether they have been attached correctly.

Once again, switch off the power, release the capacitor and recheck the wire connections. Once you are satisfied that the AC unit is functioning properly, restore the access cover.

These are the six steps of how to replace capacitors on AC units. If you follow them to the latter, your AC system will be up and running within no time. In case you feel you cannot go through this alone, get in touch with a technician to help you in replacing it. The guys from Schlüsseldienst Berlin Lichtenberg shared their advice from experience.

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