The Carrier KAACS0201PTC Start Assist PTC Kit is a device specifically designed to aid compressor startup in HVAC equipment like furnaces and air conditioners. During startup, these systems require a surge of current to overcome the initial resistance of the fan motor. The PTC kit acts like a temporary booster, providing this extra kick to start the compressor smoothly and efficiently. https://www.partshnc.com/start-assist-ptc-kit-2