the 8402-078BX is the manufacturer’s updated part number

preventing the motor overheating and high energy consumption associated with degraded dielectric film

Look for physical bulging at the top of the canister or use a multimeter to check if the capacitance has dropped more than 10% below the 55 microfarad rating

Check the rating plate of your unit for the orifice size requirement or match the S1-9951-0981 part number against your model's technical service manual

MARS 12790 Run Capacitor the 8402-078BX is the manufacturer’sThe MARS 12790 dual run capacitor is a heavy duty 50 5 MFD 440V round capacitor designed for high performance HVACR motor and compressor applications. This dual rated component provides the necessary capacitive phase shift for both the compressor and the condenser fan motor, ensuring efficient start up and lower running amperage. Built to EIA 456 A standards, it features a metallized polypropylene film dielectric housed in a rugged aluminum casing.