What Is the Difference Between the Start and Run Capacitor?

Your air conditioner is vital to maintaining comfort in your home, especially during hot summer days. When you switch on your AC, numerous components work together to cool your space effectively. Among these, capacitors play a crucial role. These components are essential for powering your air conditioner, enabling it to operate efficiently. Without capacitors, your system simply couldn't function.

There are two main types of capacitors within your AC unit: start and run capacitors. Each serves a unique function that is vital for the proper operation of your air conditioning system. Understanding the role of each type of capacitor will help you better diagnose issues and ensure your unit receives the appropriate maintenance or repairs.

In this article, we’ll explore:

An AC capacitor is a cylindrical device that stores energy. Its goal is to supply your air conditioner's motor with the power it needs to function properly. Without a properly working capacitor, your AC unit must work much harder to cool down your home. This can cause your energy bill to spike and strain your unit considerably. It's important to address any issues with your capacitor immediately because they can impact your entire HVAC system.

The start capacitor is responsible for providing the initial surge of energy that your AC unit needs to run. This electrical push comes as a current that activates the motor rotation. As the current gradually builds up, the motor begins to rotate with the field of current. Start capacitors also allow the motor to be quickly cycled on and off. They stay energized until the motor reaches 75% of its maximum speed and are removed from the circuit to prevent an overload.

Unlike start capacitors, which only provide an initial burst of energy, run capacitors are designed for continuous use. They remain energized the whole time the AC motor is running. Once the start capacitor provides that initial current to get the motor going, the run capacitor boosts the current to keep the air conditioner working. The main purpose of a run capacitor is to maintain a charge to keep the AC unit performing at its best.

Both capacitors work in tandem to keep your HVAC system functioning at optimal performance. The run capacitor essentially picks up where the start capacitor left off and provides supplemental energy to keep your AC running. Without the run capacitor, the start capacitor would eventually burn out trying to maintain such a high level of energy, which could lead to electrical issues. Likewise, the run capacitor relies on the start capacitor to set the whole process in motion before it can continue.