SS1P ActronAir 1PH Soft Starter "SS9R8" I Fits SRA, SRD, SRE M is the factory-fitted single-phase Scroll compressor (Scroll-R22-1Ph) for Classic Series and ESP Plus residential and commercial split ducted systems, compressing R22 refrigerant to drive the system's heating and cooling cycle at the heart of the outdoor unit. A failed compressor causes complete system shutdown -- neither cooling nor heating is available until a replacement compressor is installed. Isolate power and recover all refrigerant before replacement -- compressor replacement must be performed by an ARCtick-licensed refrigeration technician.