HVAC Repair Tips


An HVAC system works properly only if all of its components are functioning smoothly. When an air conditioner doesn’t cool or doesn’t turn on, we usually think about things like the circuit breaker and air filters, but a cause of these problems can be a bad capacitor as well. Once a capacitor malfunctions, the only solution is to replace it. You must note that an AC capacitor should be checked or replaced by an air conditioning repair service because it holds charge and mishandling it can cause injury or death.

What Is An Air Conditioner Capacitor?

Before anything, those who don’t know what an AC capacitor is would want an introduction to this component. So, follow below:

An air conditioner capacitor is a small cylindrical device that’s located in the outdoor unit of an HVAC system. It holds charge and provides the initial jolt of power to the motors (the fan motor and the compressor) for it to turn on. After this, the capacitor gives a steady flow of charge to the compressor until the compressor cycles off. The process repeats when the home requires cooling again.

Keep in mind that there are two fan motors and one compressor in an HVAC unit. The fan motors run continuously till the AC is powered on while the compressor cycles on and off as required.

Some people may wonder that an air conditioner receives power from the home’s electrical system so what’s the need for a capacitor? The reason is that a compressor requires much higher power to start and function which a home’s electrical system can’t provide. This is why capacitors are used that store charge and provide it to the compressor for starting and running.

Signs Your AC Capacitor Is Failing

No Cool Air

If you notice that your AC is not blowing cool air or there is insufficient cooling, the capacitor may be to blame. However, you must look for other signs mentioned here because no cooling is a common problem and many issues can cause it such as incorrect thermostat settings, dirty air filters, lack of maintenance, blocked ductwork, air duct leakage, low refrigerant, and others.

You can try to turn your AC off and after waiting for a minute, turn it on. Plus, take a look at the thermostat as well. But if the problem persists, it’s better to consult an expert so they can detect the cause of the issue.

No Airflow

Mostly, when an air conditioner is not cooling due to any problem, you still feel warm air coming from the vents. However, in case of no airflow, you should consider replacing the capacitor because it powers the fan motors. Moreover, you should check the vents if they are closed or clogged. Plus, an expert should take a look at fan motors as well.

The AC Doesn’t Turn On

As we have learned earlier, a capacitor gives power to the compressor and fan motors of the AC to turn on, what would happen if the capacitor malfunctions? It won’t be able to give power to the motors so the AC won’t turn on.

You should note that like other AC problems, there are many potential reasons for an AC not turning on. It can be a bad capacitor, but you should also check the power cord of the air conditioner, the power outlet, and also look for a flipped circuit breaker.

Your AC Turns Off Abruptly

In normal circumstances, an AC should turn off when you power it off. However, if your AC shuts off suddenly without warning, the cause of this problem is likely a malfunctioning capacitor. Mostly, this issue is accompanied by a clicking noise.

To be sure, you should turn on your AC to check if it suddenly turns off again. Moreover, apart from the capacitor which should only be checked by a professional, you should look for a damaged power cord, damaged power outlet, any burning smell of the wiring, and a blown or flipped circuit breaker because they can trigger a similar problem.

Delayed AC Startup Or Cooling Cycle

As a capacitor starts wearing out, it becomes weak and can’t hold enough charge to quickly turn on the motors when you power on the AC. Due to this, you notice a delayed AC startup. Similarly, when the temperature drops, the compressor turns on for cooling. If the compressor turns on much later than it should, it also hints at a weak capacitor. Have an expert check the capacitor and replace it.

Higher Energy Bills

With more frequent HVAC usage, energy bills rise. It’s a no-brainer. However, if your usage of the air conditioner is normal, but your power bills are increasing every month without any explanation, then your air conditioner may be a reason for it.

A common cause of this can be a weak or bad capacitor. Because when the capacitor is unable to give the motors power, they either don’t turn on or they turn on, but use more direct electricity. When your AC keeps working like this, your energy bills rise.

Other reasons for this could be dirty air filters, a dirty outdoor unit, clogged ductwork, low refrigerant, or an issue with any other important AC component.

Humming Noise

This humming noise is different from the regular noise you hear when the AC works. If you hear any humming noise that’s not the regular one, it may be due to a problem with any component. Most commonly, it’s the capacitor. It happens because the capacitor can’t start the motor as it should. As the motor struggles to start, you hear this humming noise.

Burning Smell Or Smoke

Look for smoke near the outdoor unit or a burning smell because it can be a sign of a bad capacitor. When a faulty capacitor can’t provide enough power to the motor, it works harder and overheats. This is an alarming sign as it can cause a fire if you don’t act quickly. So, if you notice this sign, you should immediately turn off the AC and consult an expert.

Swollen Capacitor

If you know the location of the capacitor, you can remove the cover and take a look at it. A faulty capacitor is swollen. However, it’s advised not to touch the capacitor or its wiring even when the AC is disconnected from power because a bad capacitor can also have some charge stored that can cause an injury if touched.

Old Capacitor

An AC capacitor lasts between 5 to 20 years. So, if your capacitor was last replaced 5 years ago, you should look for the above-mentioned signs. In case you never replaced the capacitor, consider AC capacitor inspection after 8 years of AC installation.

However, if your HVAC system overheats or had some other wiring-related issue, you must get the capacitor checked as well because it may have been damaged due to that problem.


A capacitor is a commonly replaced part of an HVAC system. So, if you notice these signs, your AC’s capacitor might also require a replacement. As mentioned before, a capacitor stores high voltages of charge. So, you must hire an HVAC repair service McLean for its inspection or replacement.



Your email address will not be published. Required fields are marked *