What Causes a Capacitor To Fail in an Air Conditioner?

Air conditioners and heat pumps rely on a number of parts to keep your home comfortable. Some of them don't sit in plain sight, but your unit will not function without them. One such part is the capacitor.

These small components play an integral role in your air conditioner's function. Thus, you will surely feel the impact if it fails. As Belleview's AC repair experts, we receive many emergency calls that turn out to be capacitor problems. Most customers ask, "What causes a capacitor to fail in an air conditioner?" We provide the answer in this blog post.

What Is an AC Capacitor?

You'll find the AC capacitor, a small cylindrical component, inside your air conditioner. It holds around 400-600 volts of electricity which it uses to jumpstart your system when you turn it on.

Many air conditioners have two types of AC capacitors:

• The start capacitor. It delivers the electricity necessary for starting the AC fan motors. Once they kick in, the capacitor stops working.
• The run capacitor. The run capacitor sustains the AC's operations. It produces a magnetic field that keeps the AC coil motors running for as long as you need the air conditioner.

Your air conditioner will stop working if any of these capacitors break down.

Reasons for Capacitor Failure in an Air Conditioner

So, what causes a capacitor to fail in an air conditioner? We'll look at the main reasons below:

Overheating

Overheating is one of the main causes of failure in capacitors. A capacitor with internal temperatures reaching above 150°F frequently will fail at its task of holding a charge. Unfortunately, many reasons will cause an AC capacitor to overheat:

Direct Exposure to Sunlight

The temperatures outside on Florida's hottest summer days can reach 90°F or higher. Having the condenser unit directly under sunlight means a bulk of those rays will reach the capacitor. Add the heat from the condenser unit while the air conditioner works hard to cool your home, and it's easy for the capacitor to overheat.

Dirty Filters

Your air conditioner will work harder than necessary if you don't change the filters at the right time. Clogged air filters reduce the flow of air from the return ducts to your evaporator coil. If you ignore the dirty filters long enough, the capacitor will overheat.

Dirty Coils

You need to clean your AC coils regularly to ensure consistent heat exchange between the surrounding air and the refrigerant. If you have dirty coils, the system (and the capacitor) will overheat while working harder than usual to cool your home.

Refrigerant Leaks

If your air conditioner has refrigerant leaks, it will overcompensate by running longer than normal. The extra strain will likely cause the capacitor to overheat and fail.

Lightning Strikes and Power Surges

Any kind of power surge will disable your capacitor. So lightning strikes during storms and power supply issues can blow out the capacitor.

Undersized Capacitor

When you attempt a DIY capacitor replacement or hire unqualified personnel to change your capacitor, they may replace the damaged unit with one that has a lower voltage and capacitance rating. With the improper voltage, the new capacitor will fail relatively quickly.

You might wonder if it's okay to use a capacitor that has a higher voltage and capacitance rating. Interestingly, many technicians will recommend using an "oversized" capacitor.

Capacitor Age

Capacitors act no differently from other electrical components. They can fail over time due to normal wear and tear. Unfortunately, it's hard to put a lifespan on capacitors, but you should expect yours to last a decade or more easily, all other things being equal.

Sometimes, the wear and tear doesn't happen directly to the capacitor. If the connectors become loose or rusty, your capacitor will likely fail.

What Are the Signs of Air Conditioner Capacitor Failure?

One of the first signs of a failed capacitor includes your home becoming cooler (or hotter for heat pumps) than your set temperature. If the run capacitor is the problem, you'll notice the air conditioner fan running, but you won't feel any cool air.

If the start capacitor is the problem, the air conditioner will not kick in at all. If your air conditioner doesn't respond, first check your breaker panel to ensure you don't have a tripped breaker. If the breaker isn't the problem, you likely have a failed capacitor.

You can complete a visual check before calling a professional to help you change the capacitor. To check the capacitor, you can follow these steps:

• Unscrew the side panel of your outdoor unit to find the capacitors (cylindrical components with a shiny body and wires connected to the top)
• Check the units to see if they are swollen at the top or bottom
• Check for leaks around the bottom or top

If you spot swelling or leaks (dielectric fluid), you have a failed capacitor.

Is Capacitor Replacement a DIY Job?

No. Don't consider capacitor replacement a DIY job. You should leave this task to a qualified HVAC technician. As we discussed above, these units can pack up to 600 volts of electrical charge. You run the risk of electric shock if you mishandle the capacitor at any stage of the replacement.

Improper installation can also trigger an electrical fire inside your home. So forget the YouTube tutorial and save yourself from costly repairs—or worse.

Instant Help When Your Capacitor Breaks Down

Now that you know what causes a capacitor to fail in an air conditioner, you have to take steps to prevent failure from any preventable causes. One way to achieve this involves scheduling regular maintenance for your HVAC system with a professional HVAC company.

If your capacitor breaks down despite your best efforts, don't despair! You can trust the team at Fast Air Repair to provide a speedy resolution. We'll replace your failed capacitor with a matching and highly durable unit that will support efficient cooling.

Call the Fast Air Repair team in Ocala, FL, today at (352) 290-7968 to book an appointment for this and other common air conditioner problems.