Introduce A/C Start capacitor and run capacitor

01.10.2013 in Blog by


Introduce A C Start capacitor and run capacitor

If your air conditioner is not turning on, taking a long time to warm up or not running at full capacity, what you may need is a new ac capacitor. There are two kinds of air conditioning capacitors, and the first thing to know is which kind you need depending on what problem you are having.

1. Start Capacitors
Start capacitors are used during start up to help produce enough torque to bring the motor to full speed. Designed for momentary use, the start capacitor disconnects from the motor after it starts to prevent damage. If your air conditioner is not turning on, or is taking a lot longer to get up to full speed, then a new start capacitor is probably what you need.

In hot environments, this capacitor may be over worked and fail prematurely. At this point, a replacement will need to be obtained to bring the system back online. Fortunately, these are very simple to select. Start with the voltage, then capacitance, and finally, you’ll need to verify that the capacitor selected will fit within the space available by checking the measurements.

2. Run Capacitors
The other common type of capacitor is the run capacitor, which maintains a constant voltage supply to the motor and increases their torque at star tup and efficiency once the motor is running. All run capacitors are designed for continuous duty, and have a much lower failure rate than start capacitors. There are two types of run capacitors: single unit and dual-run. If your air conditioner is starting up without a problem but then doesn’t seem to run as well as it used to, then the run capacitor is most likely your problem.

The main difference between a start and a run capacitor is that the start capacitor has a much higher ability to store charge, also known as its capacitance rating, for its size than that of the run capacitor. While the start capacitor gives the motor a boost of energy in order to get it up and running, and then cuts off, the run capacitor keeps the motor going for rest of the time it is turned on.

For this reason a run capacitor can, in some circumstances, be used as a start capacitor, as long as the capacitance and voltage ratings of the original start capacitor are the same as the replacement. A start capacitor can never be used as a run capacitor, though, simply because it could not handle the continuous current and would burn out.

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