How to Tell if Your AC Capacitor is Bad

Signs AC Capacitor is Bad

If your air conditioner is not working properly, you may be concerned about the cause for the malfunction — and how much it’s going to cost to fix it. While the culprit could be many issues, a common cause is a faulty capacitor. But what exactly is a capacitor? And what are the signs that it’s gone bad?

What is an AC capacitor?

Capacitors are small, cylindrical or cuboid parts responsible for providing energy to a motor. In AC units, they furnish the energy necessary for the unit to turn on as well as to keep running. Since the capacitor is such a vital and hard-working part of the AC unit, over time its efficiency is diminished by regular wear and tear.

5 Bad AC Capacitor Symptoms

If your AC unit is not working properly, here are some signs it might be due to a bad capacitor:

1. AC Unit Takes a While to Start After You Turn It On

Since the capacitor is responsible for the initial energy required for the unit to begin operating, an air conditioner that’s struggling to start may be due to a faulty or worn out capacitor.

2. AC Unit Shuts Off on Its Own

The capacitor is also responsible for providing the energy your AC unit needs to keep working after you turn it on. If the AC system is shutting off randomly, therefore, it may be because the capacitor has gone bad and is no longer capable of delivering that continuous charge.

3. AC Unit Makes Clicking or Humming Sound While Running

A clicking or humming sound from your AC unit is a sign that the motor is having trouble. If the capacitor has gone bad, the motor will still attempt to operate — but without the power necessary to do so, the motor can overwork and burn out, leading to major damage that can come with a hefty price tag.

4. AC Unit Won’t Start

If the capacitor has fully gone bad, the AC unit’s motor will receive no power and your AC won’t turn on at all.

5. AC Fan Stopped Working

If the fan has stopped spinning on your AC unit even when it’s turned on, a bad capacitor may be to blame. To test if the fan malfunction is due to a faulty capacitor, you can do the following: walk outside to where the AC condenser unit (the big outdoor box) is located. If the AC is turned on but the fan isn’t spinning, use a long branch to push one of the fan blades. If the machine comes to life after a little push, it’s almost certainly a bad capacitor.

If you don’t feel comfortable testing this out on your own, have a licensed technician come out and inspect the unit for you. They will also be able to advise you on any repairs that might be necessary.

Can you replace a capacitor on your own?

While we advise seeking the assistance of a professional, the answer is yes — it is possible to replace a capacitor on your own. Before replacing the old capacitor, make sure to note the voltage rating (labeled as V on the old capacitor) and microfarad (labeled as μF). This is crucial since the microfarad of the new capacitor has to be exactly the same as the old capacitor. Other than these two factors, the size or shape of the capacitor won’t matter.

How to Replace Your AC Capacitor

Once you have the correct replacement part, follow these steps:

Step 1. Turn off the air conditioner — both at the thermostat and breaker panel.

Step 2. With a screwdriver, unscrew the back panel of the condenser unit.

Step 3. Locate the capacitor. If you don’t know what it looks like, click here.

Step 4. Take a picture of the connectors (labeled HERM, fan, and C), so that you know how to connect them correctly once you install the new capacitor.

Step 5. Disconnect the old capacitor.

Step 6. Install the new capacitor, following the manual’s instructions.

Step 7. Reinstall the back panel on the condenser unit.

Step 8. Remember to turn back on the AC at the breaker panel.

If the process sounds confusing or you don’t want to deal with it yourself, you should contact a licensed technician to do it for you. Another advantage of doing so is that the HVAC professional can notice any additional issues that may later become a problem with your AC — such as a failing compressor, a blown fuse, or diminished airflow. Having a technician regularly provide maintenance to your air conditioner will ensure the system runs efficiently, which saves you money on your monthly energy bill and lasts as long as possible.

AC Service in Brevard County

At Colman Air, we understand that sometimes, AC issues happen during the most inconvenient times. This is why we have a 24/7 AC emergency line. Call us if you need assistance ASAP, if you’d like to learn more about faulty capacitors, or to schedule routine HVAC maintenance.

24-HR Emergency Service: (321) 360-7566

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