Dual Run Capacitors

Dual Run Capacitors

Dual run capacitors are commonly used in HVAC (heating, ventilation, and air conditioning) units. Dual capacitors have three terminals, unlike regular run capacitors, which have only two. Electrically, they are the same as run capacitors that have two terminals. Using a dual run capacitor allows you to save space if you have a small mounting area. The terminals are also clearly marked, making it easy to hook it up to the different components of your air conditioner.

TEMCo Dual Run Capacitors

Dual capacitors usually have connections marked "C" for "common," "H" or "HERM" for the hermetic compressor, and "F" or "FAN" for the fan in an HVAC unit. They also have two different capacitance ratings (for exampple, 35/5 uf). The larger value is always connected to the compressor (35 uf in the example), while the smaller value will always be connected to the fan (in this case, 5 uf).

TEMCo Dual Run Capacitor Terminals

Specifications

The following specifications should be taken into consideration when selecting a new capacitor.

Capacitance

Make sure the capacitance of your new capacitor is the same as that of the one you're replacing.

Voltage

Dual capacitors are usually rated for 370V or 440V. Use a capacitor that has the same or higher voltage as your system voltage. Never select one that has a lower voltage rating than your system voltage.

Frequency

Most capacitors will be rated for both 50 and 60 Hz.

Oval vs. Round Case Style

As long as the capacitance, voltage, and frequency of your capacitor is right for your application, the shape of the capacitor does not matter as long as it can fit within the provided mounting space in your motor or air conditioning unit.

Terminal Type

Most capacitor terminals include one to four ¼" push on tabs. Most have 3 to 4 tabs, so make sure you have enough tabs per connection post to make the connections you need.

Regular vs Dual Run Capacitor

Video - Replacing a Dual Run Capacitor

Watch the video tutorial on how to diagnose problems with your air conditioning unit and how to replace the run capacitors in it.