York S1 373 39504 006 Conversion Kit Refrigerant single throw (SPST) normally open configuration single throw (SPST) normally open configuration that closes when it detects a pressure fall of Durable Construction: Engineered to withstand the acidic nature of furnace condensate and the thermal cycles of high efficiency gas heating This OEM certified compressor conversion kit provides the necessary hardware and electronic interface to drop a Gen2 compressor into a York HVAC system without extensive field modifications Reduced Operational Noise: Gen2 compressor technology is engineered for quieter cycles and smoother vibration damping compared to older reciprocating models