A dual "run capacitor" supports two electric motors, such as in large air conditioner or heat pump units, with both a fan motor and a compressor motor. It saves space by combining two physical capacitors into one case.
The dual capacitor has 3 terminals labeled "C", "FAN", and "HERM", which stand for the Common, Fan, and HERMetically sealed compressor.
Dual capacitors come in a variety of sizes, depending on the capacitance (µF), such as 40 plus 5 µF, and also the voltage.
A 440 volt capacitor can be used in place of a 370 volt, but not a 370 in place of a 440 volt.
The capacitance must stay the same within 5% of its original value.
Round cylinder-shaped dual run capacitors are commonly used for air conditioning to help in the starting of the compressor and the condenser fan motor.
An oval dual run capacitor could be used instead of a round capacitor, but the mounting strap should be changed to better fit the oval shape.