Many of our service calls are very simple: a blown capacitor. This is good for our customers because capacitors are comparatively inexpensive and quick to replace. Unfortunately, capacitors are a little bit like light bulbs. It might last 3 days. It might last 3 months. It might last 3 years, but it is very hard to tell how long they will last. Thankfully, our expert technicians at Mode Comfort can assist you with any AC issues. 

What Does a Capacitor Do?

The capacitor is the part of a unit that stores and dispenses electrical energy to make the AC or heat pump run. The electricity from the capacitor runs the motors, such as the compressor, the fan motor, and the blower. The main job of a capacitor is to jump start the AC unit or heat pump. Without the capacitor, your unit will not start consistently or run to its top capacity, leading to less quality AC. 

What is the Difference Between a Start Capacitor and a Run Capacitor?

Start capacitors give a jolt to the system to get the compressor and fan motor going. Run capacitors provide the oomph to keep the system running. They might be little, but without them, your unit is essentially dead.

How long do capacitors last for?

Capacitor lifespans can really vary based on the type of product and the conditions with which the AC or heat pump runs. The common HVAC capacitors that you see in many homes can last between 5 and 20 years. The capacitors that are used in industry-sized units can last for much longer. Thankfully, though, doing upkeep on your AC unit or heat pump can result in not needing replacement for 15 to 20 years. At Mode Comfort, we offer HVAC Inspection programs where our technicians maintain the upkeep of your unit so that your capacitor lasts as long as it can.

Why Do So Many Capacitors Fail?

1. Overheating

Capacitors fail if they are in direct sun for too long or if they run for too long, contributing to failure in the air conditioner fan capacitor. 

2. Open capacitors

Sometimes there can be breaks in the circuit of the capacitor, which stops the flow and renders the machine inoperable. 

3. Dielectric Breakdown

Sometimes AC units require high voltage capacitors, which can cause the dielectric materials within the capacitor to break down and fail.  

4. Environmental Factors

Areas that experience intense humidity or extreme weather environments may have earlier AC capacitor failure. Hermetically sealed capacitors are recommended if you live in these conditions. If your AC unit is near any sort of corrosive chemicals, this could damage your unit as well.

5. Service life

As with any appliance, AC units and heat pumps have prospective lifespans. If an AC unit or heat pump is nearing the end of its lifespan, the capacitor may begin to fail. 

6. Insulation resistance

The insulation in the machine is what keeps it from having any sort of electric shock. If the insulation begins to decrease, there can be more frequent short circuits that cause the capacitor to fail. 

7. Capacitance

The capacitance of a device describes its ability to store electric charges. Unfortunately, sometimes the capacitance can exceed the limit for a device, causing it to burn out. 

8. Vibration, acceleration & shock

Any sort of mechanical movement that is not routine for a device can disrupt the function of the mechanisms inside and cause issues with the circuit’s function. 

9. Dissipation factor

The dissipation factor (DF) for a capacitor is the measure of how much energy is lost and dispelled as heat when the AC functions. A low DF is preferred for efficient usage, but a high DF can burn a machine out quickly. 

10. Barometric pressure

Large changes in air pressure can put a lot of strain on an AC or heat pump, and can result in a faulty capacitor. 

11. Radiation

Radiation can be one of the most harmful things to impact a capacitor. If a unit is exposed to radiation, it can degrade the materials and lead to complete breakdown of the unit permanently. 

If you think your capacitor may be failing, it is imperative it is caught and replaced early. Running your unit with a failing capacitor can cause major (and expensive) damage. A dead capacitor can take out a motor or compressor with it, and possibly even cause the unit to fail entirely.

But How Do I Know If My Capacitor is Failing?

You probably won’t know the common air conditioner capacitor failure symptoms, but we will! Preventative maintenance is the key to getting ahead of potential issues. Mode’s Fan Club is only $19.95 per month (for one unit) and that includes two preventative maintenance visits per year. One inspection can cost $150-$200…you can do the math. During these check-ups, we will inspect all aspects of your comfort system, including your capacitors.

There are a few signs of possible capacitor failure modes that homeowners can look for in between check-ups to (although there can certainly be other causes to the below):

• The compressor struggles to start and then shuts off quickly
• The unit starts and stops over and over
• The AC or heat pump is not blowing cold air
• A humming noise
• A clicking noise
• Your system is performing differently than it previously had been

Can I Replace a Capacitor Myself? Or Should I Call Mode Comfort? 

We do not suggest that homeowners ever attempt to replace a capacitor themselves, as it stores an electrical charge and contains hazardous oil. This is one piece of equipment best left to the HVAC professionals.

At Mode Comfort & Air Quality, we have technicians with the expertise to ensure that any issues with your HVAC are handled with precision and speed. Contact Mode Comfort & Air Quality at 804-481-6633 or admin@modecomfort.com today to hear what we can offer you. 

FAQs:

What happens if a capacitor fails?

At first, a capacitor failing may lead to less efficient cooling, but not handling the issue can lead to permanent breakdown of the unit. 

Do capacitors slowly fail, or is it just one day they won’t work?

This can vary! Many capacitors fail over time due to wear and tear, but sometimes they can fail quickly from electrical breakdowns or damage to the machine. 

What does a blown capacitor look like?

Things you should look out for that indicate a blown capacitor in your AC unit or heat pump is a bulging top, a broken casing, leakage of electrolytic fluid, or burn marks. 

How to prevent capacitor failure in a circuit?

The best way to avoid capacitor failure is to hire regular maintenance from a trusted HVAC company. If you’re looking for quality service in the Richmond area, give Mode Comfort a call today. 

What are the common problems in capacitors?

We discuss all of the capacitor problems you may encounter in the article above, but the most common are loss of capacitance, leakages, physical damage, and short circuiting.