Winter is near; you’ll be relying on your gas furnace, which will offer a lovely ambiance. For the efficiency of your furnace, the capacitor is a modest and crucial component. Its function is an extra jolt of energy to the furnace blower motor, causing the fan to turn on. Like any other part of your furnace, a capacitor can fail and cause your furnace to cease working.
What does the furnace capacitor do?
Because your furnace consumes a lot of energy, it has a capacitor to provide the extra energy required to operate the blower. The capacitor, like a battery, stores the extra energy needed to jumpstart the furnace blower. Capacitors:
- Store and release energy as needed.
- They are capable of tolerating higher current loads and have more charge storage capacity.
- Give an extra burst of energy required to turn the blower motor and get your furnace’s fan spinning.
- It also stores energy until it is needed.
Do you need to replace a furnace capacitor immediately?
As capacitors are one of the most prevalent components on furnaces, we must give attention to any necessary replacement. But it may typically last between 10-20 years, but the variables could shorten their lifespan. If you’ve had your furnace for more than ten years, you’ll almost certainly need to replace the capacitor at some point.
What are some symptoms of a bad capacitor?
As hot air blows into your home by your furnace’s blower. If a furnace capacitor fails, the blower motor will not perform properly, putting your family’s comfort at risk. There are a variety of signs and symptoms that indicate a defective capacitor:
Power Shutdown
A faulty furnace capacitor will prohibit the blower motor from operating, leading the unit to shut down completely. Check the fuse that controls your furnace to see if it’s on before determining whether the capacitor is the source of the problem.
Increase the thermostat settings once your furnace is powered up and observe whether the blower motor starts working within a few minutes. The capacitor is most likely to be responsible if there is no response.
Inconsistency In Blower Motor
For the blower motor to work effectively, the capacitor must be in good condition. The blower motor may run slowly or inconsistently if the capacitor is defective or overheat readily. If you observe that your blower motor is acting abnormally or has short cycles, have your capacitor inspected by professionals.
Sounds of Humming
The blower’s humming sounds indicate that the capacitor is having electrical troubles. You have no choice but to pay great attention to your blower if you want to solve the problem. To do so:
- Raise your thermostat and wait for the blower on your heating system to switch on.
- Open your furnace’s access panel with a screwdriver, then lean near to your blower’s housing to hear the weird noise within.
- Schedule a professional inspection right away if you hear a buzzing sound.
Stop Blower
A faulty capacitor stops the blower. Check your capacitor soon if your unit stops operating. Make sure the fuse that controls the heating system is turned on before proceeding.
Turn increase your thermostat once the furnace is powered up and see if your blower starts to work within a few minutes. If you don’t get any response from it, your capacitor has likely failed. Call professional for thorough evaluation and diagnosis of your capacitor.
Erratic Motor Operation
Because your capacitor functions as a battery and stores the charge required for the blower motor to operate effectively, it should always be in good working order. On the other hand, your blower motor may run slowly, become excessively hot, and behave abnormally if you have a faulty capacitor. Now, if you notice that your heating system’s motor is constantly short-cycling or acting strangely, contact a professional to have the capacitor tested.
What causes furnace capacitor failure?
Every air conditioning system consists of an electric blower motor that circulates cool air within, an electric condenser fan motor that exhausts hot air outdoors, and a compressor motor that pumps refrigerant through the system.
Engines
Each motor has a capacitor to start when the thermostat turns on the air conditioner and keeps it running at maximum efficiency. Because the compressor consumes far more energy than the other two motors, the compressor capacitor is the largest.
Overheating
The moist separator inside the electrolytic A/C capacitor will dry up if the unit gets too hot, resulting in an internal short circuit. If the capacitor’s temperature consistently exceeds 150 degrees Fahrenheit.
Overloading
The air conditioning capacitor gets the compressor and fan motors up to about 3/4 of their maximum speed before disengaging them, not for constant electrical load. The capacitor will most likely overcharge and be damaged if the motor becomes physically blocked from turning or if the engine burns out. Voltage exceeding the capacitor’s rated value may also cause it to fail.
Worn-out Part
A capacitor may burn up if the compressor or fan motor drags due to damage or worn bearings. By leaving the capacitor in the circuit for too long, a faulty relay switch might cause it to overheat. A capacitor, a compressor, the fan motor, or the unit’s cables can all be damaged by lightning. Even a minor power surge might cause the capacitor to be damaged or destroyed, resulting in compressor overload and failure. A capacitor that is leaking oil is a dead giveaway that it is malfunctioning.
Life Expectancy
Normal wear will eventually cause an A/C capacitor that has been protected from damage, electrical surges, overheating or inappropriate electrical loads to fail. The lifespan of a capacitor varies depending on the temperature and usage pattern.
The Role of Dual-Run Capacitors in HVAC Systems
In some HVAC systems, a special type of capacitor called a dual-run capacitor is used. This component serves two functions, helping both the compressor and the blower motor run efficiently. A dual-run capacitor essentially combines two capacitors into one, reducing the overall number of parts in your system.
If your furnace uses a dual-run capacitor and it goes bad, you could experience issues not only with the blower motor but also with the compressor. This can make diagnosing the problem more complicated, as it can affect multiple aspects of your HVAC system. Regular maintenance is critical to ensuring all parts of the system are working well together.
How Seasonal Changes Impact Capacitor Performance
Capacitors are highly sensitive to temperature, and extreme weather conditions can hasten their failure. During winter, when the furnace is running frequently, the increased load on the capacitor can lead to premature wear. Meanwhile, during the summer, if you’re using the air conditioner frequently, the same capacitor might be involved in starting the cooling system, adding extra strain.
To minimize seasonal wear on your capacitor, it’s a good idea to have it inspected during both the heating and cooling seasons as part of your regular HVAC maintenance schedule. This way, any signs of weakness or failure can be caught before the capacitor completely fails, leaving you without heat in the middle of winter.
Capacitor Types: Start vs. Run Capacitors
HVAC systems often use two types of capacitors: start capacitors and run capacitors. Start capacitors provide the initial energy surge needed to get the blower motor going, while run capacitors provide a steady supply of power to keep the motor running smoothly. When troubleshooting HVAC capacitor issues, it’s important to understand which type of capacitor is malfunctioning.
- Start Capacitor Failure: If the start capacitor fails, your blower motor may struggle to turn on. You might notice your furnace attempting to start but failing to get going.
- Run Capacitor Failure: If the run capacitor fails, your blower motor may start but will operate inefficiently or inconsistently, leading to erratic operation or short-cycling.
A qualified HVAC technician can identify which type of capacitor has failed and make the necessary replacement.
Preventative Measures to Extend Capacitor Lifespan
While capacitors have a natural lifespan and will eventually fail, you can take several steps to extend their life and keep your HVAC system running smoothly for as long as possible:
- Regular Maintenance: Scheduling routine HVAC maintenance, where a technician checks all components—including the capacitor—can help catch problems before they escalate. Cleaning dust and debris from your furnace components also reduces strain on the blower motor and capacitor.
- Surge Protection: Power surges, which can occur during storms or due to fluctuations in your home’s electrical grid, can damage the capacitor. Installing surge protectors can safeguard the capacitor and other sensitive components from sudden voltage spikes.
- Temperature Control: Try to maintain a stable temperature in the rooms where your furnace and HVAC equipment are located. Extreme heat or cold can accelerate capacitor wear. For example, if your HVAC unit is located in an attic or garage, insulating these areas can help mitigate temperature swings.
Capacitor Size and Compatibility
When replacing a faulty capacitor, it’s important to ensure the new part is the correct size and type for your furnace. Capacitors are rated by both voltage and microfarads (µF), which measure the amount of charge they can store. Installing a capacitor with incorrect specifications can lead to inefficient operation or even damage other parts of the system.
Always rely on a professional HVAC technician to select and install a compatible capacitor. Using the wrong capacitor, or one with a different voltage or capacitance rating, can overburden your furnace’s blower motor or other components, leading to premature failure.
Signs of Overheating and Other Physical Damage
Capacitors are particularly vulnerable to physical damage, which can manifest as bulging, leaking, or corrosion. Overheating is a common cause of capacitor failure and can occur due to:
- Overuse of the HVAC system, especially during extreme weather conditions.
- Poor airflow around the furnace or HVAC unit, leading to overheating of internal components.
- Issues with the blower motor itself, such as worn bearings or blocked airflow, which forces the capacitor to work harder than it should.
If you notice any physical signs of damage—such as a bulging or leaking capacitor—turn off your furnace immediately and contact a technician. Continuing to operate the furnace with a damaged capacitor can risk further damage to other components of the HVAC system.
Environmental Factors that Contribute to Capacitor Failure
The environment in which your HVAC system operates can also impact the longevity of the capacitor. High humidity levels, for example, can corrode capacitor components, especially if the furnace is located in a basement or crawl space prone to moisture. Conversely, a dry, dusty environment can clog the furnace’s air filter, putting additional strain on the blower motor and, in turn, the capacitor.
Proper ventilation and humidity control can help protect your HVAC system and its components from environmental wear and tear. This is another reason why regular maintenance is key—technicians can assess the condition of the system based on environmental factors and suggest measures to mitigate any potential risks.
When to Replace Your Capacitor
While some capacitors can last up to 20 years, most fail between 10 and 15 years. It’s essential to recognize the early signs of failure, such as slow blower motor operation, strange noises, or erratic performance. Replacing the capacitor before it completely fails can prevent more costly damage to the blower motor or other HVAC components.
If your furnace is over 10 years old, it might be wise to proactively replace the capacitor during routine maintenance, especially if you’ve noticed any warning signs. A new capacitor is a relatively low-cost investment compared to the expenses of replacing a blower motor or other major components.
Conclusion
The capacitor in your HVAC furnace plays a vital role in ensuring the smooth operation of the blower motor, which is critical for proper heating during winter. Recognizing the symptoms of a bad capacitor, understanding the various types of capacitors, and taking steps to extend its lifespan can help keep your furnace running efficiently. Regular HVAC maintenance, professional inspections, and taking preventative measures can minimize the risk of unexpected breakdowns and keep your home warm and comfortable throughout the colder months.
Whether you need capacitor assessment, maintenance, or installation, you can trust that we’ll do everything we can to keep you comfortable and safe. Our technicians are ready with methods and techniques to keep your cooling and heating systems in top shape all year. Don’t hesitate to get in touch with us right away. Fill out the contact form below an we will answer any questions you have about your HVAC system.
