ActronAir Compressor Run Capacitor P2/S2 50uF 450V provides the phase-shift capacitance required for single-phase compressor starting and continuous running on compatible ActronAir residential split ducted systems rated at 50uF. The compressor run capacitor sustains the auxiliary winding current that produces starting torque -- a failed or degraded capacitor causes the compressor to fail to start, drawing locked-rotor current until the motor protector trips. Isolate power at mains before replacing any capacitor components.