Exploring the Causes of HVAC Capacitor Failure

The HVAC capacitor plays a vital role in the proper functioning of your heating and air conditioning system. It stores and releases electricity to start the fan and compressor motors. Unfortunately, capacitors can fail over time for numerous reasons. By identifying the causes behind this issue, homeowners can take preventative measures to ensure their HVAC systems run smoothly.

Age and Wear

The average lifespan of an HVAC capacitor ranges between 10 and 20 years. Over time, the internal components can degrade, leading to reduced performance and eventual failure. Regular maintenance can help monitor the condition of capacitors, and, depending on the technician’s recommendation, replace them before they fail.

Voltage Fluctuations

Voltage fluctuations caused by power surges, electrical storms or unstable power grids can strain capacitors. Excessive voltage can damage the capacitor’s insulation and lead to premature failure. Installing surge protectors or voltage stabilizers can help mitigate the impact of voltage fluctuations.


Capacitors generate heat during operation, and excessive heat can degrade their components. Poor ventilation, high ambient temperatures or proximity to other heat-producing components can cause overheating. Adequate airflow and proper capacitor placement can help prevent overheating.

Poor Manufacturing Quality

Capacitors of low-quality manufacturing can be susceptible to premature failure. Inexpensive components may not be built to withstand the demands of continuous HVAC operation. Investing in high-quality capacitors during repairs or replacements can extend the lifespan of the HVAC system.

Incorrect Voltage Ratings

Using capacitors with incorrect voltage ratings can lead to failure. The capacitor’s voltage rating must match the system’s requirements to ensure proper heating and air conditioning. Installing capacitors with higher or lower voltage ratings can result in undue stress, leading to failure.

Dust and Debris

Dust, dirt, and debris can accumulate on capacitor terminals, which may lead to electrical leakage or short-circuiting. Regular cleaning and maintenance can prevent debris buildup and maintain the integrity of the capacitor.

Electrical Imbalance

Capacitors can experience electrical imbalance due to unequal voltage distribution across the terminals. This can happen if the system experiences power fluctuations or if the capacitor’s connections are loose. Balanced electrical distribution is crucial to preventing stress on the capacitor.

Corrosion and Rust

Exposure to moisture, humidity, and corrosive environments can lead to the corrosion of capacitor terminals. This can weaken the connection and disrupt electrical flow, ultimately causing capacitor failure. Keeping the HVAC system in a dry and clean environment helps prevent corrosion.

Frequent Power Cycling

Frequent on/off cycling of the HVAC system places additional strain on capacitors. This is common in regions with temperature fluctuations. Minimizing unnecessary power cycling and ensuring efficient thermostat programming can reduce the stress on capacitors.

If you are in Irvine, CA, and need a dependable HVAC service, contact Kemnitz Air Conditioning & Heating at (949) 453-8500, or fill out our online form. We’re here to assist you with heating and AC repair, installation, and maintenance. We serve clients in Orange County and the surrounding communities.

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